China announced the end of its hugely controversial one-child policy on Thursday, after decades of strict, sometimes brutal enforcement left it with an ageing population and shrinking workforce that has heightened the challenges of slowing economic growth.

All couples will be allowed two children, the official Xinhua news agency reported, citing a communique issued by the ruling Communist Party following a four-day meeting in Beijing.

The historic change was "intended to balance population development and address the challenge of an ageing population", Xinhua said.

Campaigners welcomed the move, but stressed that a "two-child policy" still meant that China would retain population control mechanisms -- while demographic changes will take decades to have an effect, and previous loosenings led to fewer extra births than expected.

The policy, instituted in the late 1970s, restricted most couples to only a single offspring and for years authorities argued that it was a key contributor to China's economic boom and had prevented 400 million births.

It was enforced by a dedicated national commission with a system of fines for violators and often forced abortions, leading to heartrending tales of loss for would-be parents.

The policy led to sex-selective abortions or infanticide targeting girls, because of a centuries-old social preference for boys.

Rural families were already allowed two children if the first was a girl, while ethnic minorities were allowed an extra offspring, leading some to dub it a "one and a half child" policy.

As a result China's population -- the world's largest at 1.37 billion -- is now ageing rapidly, gender imbalances are severe, and its workforce is shrinking.

The concerns led to limited reforms in 2013, including allowing couples to have two children if either of them was an only child, but relatively few have taken up the opportunity.

Human rights organisations welcomed the change to the deeply unpopular policy, but expressed reservations about remaining controls.

It was "good news for the couples who wish to have a second child," Maya Wang of Human Rights Watch told AFP, but "the restrictions on reproduction rights remain in China".

Amnesty International's William Nee said on Twitter: "'Two Child Policy' won't end forced sterilisations, forced abortions, gov control over birth permits."

Chen Guangcheng, one of China's best-known activists who fled to the United States in 2012, said "everybody needs to be circumspect" about the announcement, stressing Beijing was retaining population controls.

"They're still maintaining strict control on something that should be everyone's right. They need to eliminate it entirely," Chen said.

- Vested interests -

The Communist leadership met in Beijing to discuss ways to put the country's stuttering economy back on a smooth growth path as it struggles with structural inefficiencies and outdated social policies.

Known as the fifth plenum, the conclave discussed the next Five-Year Plan for China -- the 13th since the People's Republic was founded in 1949.

Over four days of meetings the 205 members of the Central Committee, plus around 170 alternates, examined the specifics of the plan, which will be approved by the country's rubber-stamp legislature next year.

China has enjoyed a decades-long boom since the ruling party embraced market economics and opened up to the rest of the world from the late 1970s.

The process has transformed the livelihoods of hundreds of millions of people and propelled the country to global prominence.

But growth has been slowing for several years, and analysts have long urged Beijing to embrace further liberalisation to avoid falling into the stagnation of the "middle income trap", when developing countries fail to fulfil their full potential.

The conclave said the economy would "maintain medium-high growth", and that China would reduce controls on "pricing products and services in competitive sectors", according to Xinhua.

Bureaucratic resistance and vested interests are strong in China, and the government has found it difficult to change the nation's course, even on issues where there is general agreement, such as family planning.

Yong Cai, a sociology professor at University of North Carolina, Chapel Hill and expert on the one-child policy, said the change announced Thursday was "at least 10 years later than it should be".

"But better than never," he added.

- Intense pressures -

As the country has grown wealthier, couples have increasingly delayed having even one child as they devote more time to other goals, such as building their careers.

"There's a lot of opportunity cost to having children. The norm has changed to one or none," said Joan Kaufman, Director of the Columbia Global Centers East Asia and a long-time expert on China's population planning.

"I don't think you're going to see a massive unleashing of this pent-up desire for children."

The Chinese public met the announcement cautiously, with many saying the change would only add to the already intense social and financial pressures attached to reproduction.

"I will have four parents to take care of, along with two children," noted one online commenter. "This is too great a responsibility".

Wu Bohao, a 23-year-old single child, told AFP: "Raising a child is quite expensive. For me, having one kid would be enough."

Victims of China's controversial one-child rules
Beijing (AFP) Oct 29, 2015 - Beijing says the one-child policy has played a key role in the country's economic success, but the controversial rule inflicted physical, emotional and financial pain on millions of ordinary Chinese.

There was a global outcry in 2012 when Feng Jianmei was forced to undergo an abortion seven months into her pregnancy, after failing to pay a 40,000 yuan ($6,300) fine.

Photos of her lying next to her bloody, dead foetus caused outrage when they circulated online, providing a rallying cry for activists who said forced abortions were a regular occurrence.

The procedure was performed past the legal limit of six months and authorities were forced to pay 70,000 yuan in compensation, but Feng's lawyer said the money would never compensate for the lifetime of "spiritual pain" the family would have to endure.

Two officials involved were sacked and five others received minor punishments, though Feng, the lawyer, and many ordinary Chinese called the punishments insufficient.

The rules have often been enforced unevenly, with China's best-known film director Zhang Yimou admitting having four children.

He was only forced to pay a fine of $1.2 million after rumours began circulating online, but many argue that financial penalties are an ineffective deterrent for wealthy families who can afford them.

The regulation also led to sex-selective abortions, especially in rural areas where boys are prized over girls.

Reports of infanticide targeting girls were also common, with propaganda painted in large red characters across the countryside urging families to do away with the centuries-old preference for a male heir.

An activist who highlighted the issue of forced abortions under the policy, blind lawyer Chen Guangcheng, was jailed for over four years.

He fled his village for the United States in 2012, after tackling the authorities on other thorny issues such as pollution, discrimination and corruption.

This year a Chinese company came under for fire for plans to demand its employees seek approval before becoming pregnant and fine those who conceive a child without permission, in an echo of the national policy.

"Only married female workers who have worked for the company for more than one year can apply for a place on the birth planning schedule," read a policy distributed by a credit cooperative in Jiaozuo, in the central province of Henan.

"The employee must strictly stick to the birth plan once it is approved," it added. "Those who get pregnant in violation of the plan such that their work is affected will be fined 1,000 yuan ($161)."

Cases of abandoned babies -- such as a newborn girl who was found crying alone in a Beijing public toilet in August -- have also been linked to the one-child law.