Days after Communist China's founding father Mao Zedong died 40 years ago the problem of what to do with his corpse was becoming increasingly heated -- literally.

Mao himself had requested cremation, but powerful officials including his mercurial widow Jiang Qing decided he would join the likes of Vladimir Lenin and Ho Chi Minh in being embalmed and put on display.

Before the natural processes of decay could take hold, Xie Piao, an official overseeing an experimental thermoelectric cooling project, was summoned in the middle of the night and tasked with cooling the corpse.

"No one expected that Chairman Mao would die, so there were no preparations at all," said Xie, now 75, who said he then felt "quite proud" to be involved in preserving the Great Helmsman's body.

He arrived at the cavernous Great Hall of the People four decades ago on Sunday to find the prostrate body of the man who led the Communist party to victory, founding the People's Republic before plunging it into chaos, in a hastily-constructed glass and wood coffin, at room temperature beneath hot electric lights.

"Our aim was to get the temperature down to 4 or 5 degrees Celsius (39-41 degrees Fahrenheit)," he told AFP, adding that some 400 people were involved in the entire project.

"We couldn't freeze him - that was his doctors' order," Xie told AFP.

At the time Chinese refrigeration systems were basic. With Soviet relations still on a war footing, asking Moscow for help was unthinkable and its ally Hanoi rebuffed calls from Beijing for assistance, Xie said.

"I thought the technology was very reliable, it was very simple," he said in what is believed to be his first interview with foreign media.

"The fear came later."

-- 'Experimental technique' --

Within hours nitrogen gas surrounding the corpse had been bought down to a cool eight degrees Celsius. But that did not prevent Mao's anointed successor Hua Guofeng berating Xie for using "experimental" techniques.

Senior leaders arrived day and night to bow before the body, adding to the seven-strong refrigeration team's tensions.

"Once I was so tired I fell asleep in the middle of work. We had no time to sleep for five, seven days," he said.

Mao's death on September 9 1976 is seen as bringing to an end the destructive decade of "Cultural Revolution" he unleashed on his nation.

But the period's intense political atmosphere still permeated the corridors of the Great Hall.

"It was very serious, no one chatted," Xie said.

When Jiang arrived to pay respects to her husband, Xie hid among the floral tributes for fear of becoming a focus for her notorious temper, according to an account he published for the first time this year.

Eight days after arriving at the Great Hall, Xie's work was declared complete.

He knows little of the embalming, said to have involved draining the corpse of fluids and injecting it with the chemical preservative formaldehyde.

Mao's former doctor Li Zhisui published a ghoulish account of the process, describing the former ruler's head swelling up "like a football".

Xie dismisses it as "unreliable", but whatever the details, Mao was put on permanent display in 1977 in a monumental pillared memorial hall in Beijing's Tiananmen Square.

-- Waxy face --

Mao lies in a dim chamber, garbed in a grey suit, his sallow waxy face framed by thick black hair bathed in a patch of orange light.

With debate about his legacy stifled by Communist authorities, he still retains a powerful hold over some sections of Chinese society and receives hundreds, sometimes thousands of visitors a day.

No detailed official account of the preservation efforts has been published.

The editorial staff of liberal intellectual magazine Yanhuang Chunqiu, or Annals of The Yellow Emperor, was purged in August, shortly after it published Xie's account, in a sign of further tightening under current President Xi Jinping.

Xie, the son of a first generation Communist who himself suffered in the Cultural Revolution, only visited the corpse once again -- in the 1980s -- and said he was "too busy" to pay any respects this week.

Top leaders also stayed away.

While still celebrating Mao, the ruling party has acknowledged the "gross mistakes" of a man whose Great Leap Forward resulted in a famine which killed tens of millions of people in the early 1960s.

Intellectuals have periodically called for his body's removal from the square.

But Xie said: "Although there is controversy, I think that Mao's corpse has been somewhat useful to China over the decades.

"The spirit of the Chinese people finds a focus on Chairman Mao's body."

Body politics: famous preserved corpses
Beijing (AFP) Sept 11, 2016 - The embalmed body of Mao Zedong lies at the symbolic centre of the Chinese Communist Party, an object of veneration for loyal cadres, and of fascination for foreign tourists.

As China marks the 40th anniversary of the death of the Great Helmsman, here are some of the world's most famous preserved cadavers.

Egyptian mummies

Say "Ancient Egypt" to any schoolchild and the first thing they'll think of is the mummies -- preserved remains of important figures.

The British Museum in London houses a collection of 120 human mummies from Egypt and Sudan, which count as one of its biggest draws for thousands of visitors.

The collection includes "Tayesmutengebtiu", or "Tamut", a high-ranking priest's daughter who lived around 900 BC, and "Tjayasetimu", a child temple singer whose mummy dates to about 800 BC.

The museum also has 300 mummified animals, including dogs, cats and even a crocodile.

None of the mummies has been unwrapped since the 1790s and museum experts have used x-rays and CT scans to carry out their research

Papuan smoked mummies

The Dani people in the highlands of Indonesia's remote, easternmost region of Papua used smoke and animal oil to preserve important elders and local heroes.

The desiccated, blackened figure of Agat Mamete Mabel, a chieftain who ruled over Wogi village some 250 years ago is one of the most notable -- decorated with pig tusks slung around the torso, a feathered headpiece, and a traditional penis gourd.

The corpse is kept in a thatch-roofed hut, where it is tended by a select few villagers.

Vladimir Lenin

Russian revolutionary leader Vladimir Lenin was the original communist leader to be embalmed, starting a trend among hard-left regimes around the world.

His corpse is permanently on display in a Moscow mausoleum, attracting visitors curious to see the Bolshevik founder of the Soviet Union.

Lenin died in 1924 aged 53, and had wanted to be buried with his mother in the former imperial capital of Saint Petersburg, but was instead preserved to lie in Red Square.

Debates on whether to remove the body started after the collapse of the Soviet Union in 1991, and increasing numbers of Russians are calling for him to be laid to rest.

Russia's Communist party has vehemently lobbied to keep Lenin in situ while the Kremlin has shown it is in no hurry to settle the debate.

Eva Peron

Eva Peron, Argentina's emblematic first lady of the 1940s and 50s, was embalmed when she died of cancer in 1952 at age 33.

"Evita" was as adored by her husband's poor and working-class base as she was reviled by the military and elite.

After Juan Peron was toppled in a 1955 coup, army officers secretly removed Evita's corpse from its resting place at a pro-Peron trade union headquarters and hid it.

Worried Peronist militants would find it, then-dictator Pedro Aramburu had the body taken to Italy and buried in Milan under a false name.

Peron's third wife and successor, Isabel, finally struck a deal: Evita's body was returned to Argentina in 1974 and she has rested ever since in her family mausoleum in Buenos Aires, a place of pilgrimage for her admirers and fans of the musical and movie about her life.

Ho Chi Minh

Although he wanted his ashes to be scattered over the country, the father of modern Vietnam was embalmed upon his death on September 2, 1969.

His body, preserved in the cold under a glass sarcophagus, has been on show since 1975 in a mausoleum dedicated to him in Hanoi.

The country has regularly called in help from Moscow in preserving the body, reflecting Soviet-era ties.

Mao Zedong

The Chinese revolutionary leader, who died on September 9, 1976, has been embalmed and on show since 1977 in a glass cubicle in the Mao Zedong Memorial Hall in Beijing's Tiananmen Square.

Mao's body was placed in formaldehyde and other preserving fluids, according to an account in the People's Daily newspaper, and today the parts of Mao's body which cannot be seen are bathed in liquid.

When the mausoleum is closed, the body is lowered into a container maintained at a low temperature, it said.

Ferdinand Marcos

Ferdinand Marcos, Philippine president for 20 years, died aged 72 in US exile in 1989, three years after he and his family fled the presidential palace in a bloodless "People Power" revolt against corruption and human rights abuses.

With periodic chemical injections to preserve it, the Marcos corpse was flown to his northern home town of Batac in 1993 to be placed in a mausoleum on public display.

Nearly three decades after his death, the corpse is both a tourist draw and political football, with the mausoleum-museum closed last month until further notice.

That was soon after new President Rodrigo Duterte granted the family's longstanding demand that Marcos be interred at Manila's National Heroes' Cemetery.

The Supreme Court blocked government preparations to hear petitions by human rights victims seeking to have the burial declared illegal.

Kim Il-Sung and Kim Jong-Il

The bodies of North Korea's founding president Kim Il-Sung and his son Kim Jong-Il are on permanent display at the Kumsusan Palace of the Sun mausoleum in Pyongyang.

When Kim Il-Sung died of a heart attack in 1994, Russian scientists helped preserve the body of North Korea's "eternal president", who now lies in a glass coffin with filtered lights to keep his face looking rosy.

The Russian team assisted with the embalming of Kim Jong-Il's body when he passed away in December 2011 -- also from a heart attack -- and is believed to be in charge of the maintenance of the bodies.

Present-day leader Kim Jong-Un and his close aides visit the mausoleum on key national holidays -- such as Kim Il-Sung's birthday -- to pay respects to his late grandfather and father.

Foreign visitors are allowed in the cavernous mausoleum twice a week -- Thursdays and Sundays -- but must dress according to a strict code and must bow before the bodies.