Once a football commentator who drew a huge following in China as he rooted out corruption in the sport, Li Chengpeng is now one of the government's fiercest critics -- and lives in fear for his own safety.

Li works on the margins of the allowed and the forbidden in China, constantly pushing the boundaries as he seeks to tell its people the truth about their own country.

He also symbolises the breadth of opinions among ordinary Chinese, with an army of seven million followers on his blog and his books on the bestseller lists, while hardline Communists brand him a traitor and see him as an object of hate.

His latest book tour saw him punched in the head, a packaged knife thrown at him, and scuffles between liberals and leftists.

"I wear a stab-proof vest now for book signings," said Li, in a rare face-to-face interview with the foreign media, sitting in a quiet, dark tea room in the southwestern city of Chengdu, his home town.

"I also employ security guards, people who know kung-fu, to help protect me," he added. "I understand there has been more discussion on the Internet by Maoists about attacking me."

A short man of average build, Li looks and acts younger than his 44 years, but despite a sometimes fidgety demeanour speaks freely and with confidence, only distracted occasionally by his fellow tea-drinkers.

Five years ago he would have been considered an unlikely target for Communist supporters.

He was one of the country's most popular football commentators -- with a fondness for English Premiership side Everton -- and, as he put it, a "typical Chinese guy" who liked playing mahjong, eating hotpot and enjoying "writing poetry, beautiful women and making money".

But everything changed with the May 2008 Sichuan earthquake, which killed more than 80,000 people in his home province.

Li travelled to the disaster zone to try to help and the carnage he witnessed at Beichuan High School, where more than 1,000 pupils died, affected him profoundly.

"This made me realise that life is precious," he said.

Li became one of the most outspoken critics -- along with dissident artist Ai Weiwei -- of shoddy building work alleged to have led to many schools collapsing across Sichuan, and the deaths of thousands of children.

"When I am not satisfied with what is going on in the world, some darkness exists in my heart," he said. "I questioned what I should do with my life. I was working for the state broadcaster, but would give it all up to write about real life."

In 2009, he set up his microblog on Sina Weibo, China's version of Twitter, where his profile soared after "Chinese Soccer: The Inside Story", a book he co-authored exposing match-fixing in the sport, was released.

In his new work, "The Whole World Knows", he wrote that Beijing's policy of drafting youngsters into the sports system and training them intensively to produce champions amounted to taking over their lives.

"The country only cares about their family life in so far as it can take over the mother's womb to give birth."

But as Li's writings focused more on political corruption, freedom of speech and the lack of other rights in the country, he began to polarise views, supported by mainly young, liberal-minded Chinese, but hated by Communist loyalists.

He is often categorised with other prominent Chinese activists, such as blind self-taught lawyer Chen Guangcheng and Ai, who he says he knows well.

But Li says he has a different agenda to the two figures, who are both more widely known overseas than in China.

"Ai Weiwei wants to tell the whole world the truth about China, but I just want my fellow Chinese to know the truth about their own country," he said.

Echoing the nationalism that drives some of his most determined opponents, he said he did not want China to be controlled by overseas powers.

"Reform can be achieved in China but we do not want to be a colony of America. China should consider the views of its own people."

Li's most extreme foes do not differentiate between government and state, so brand him a traitor for openly criticising the ruling Communist Party.

"We all love our country, but we just have different ways of showing it," he responds. "I love my country, and that is why I criticise the government. I think that scrutinising the government shows true love of one's country."

There may be signs the authorities are beginning to tolerate his brand of patriotism. Publication of his book was allowed, albeit with some censorship, and this week it was at number four in the bestsellers list.

"They know that I do not front an organisation, that I am not backed by foreign money, and I rarely give interviews to foreign media," he said.

But in a one-party state tolerance only goes so far. Li was ordered not to speak in public on his tour, and instead appeared with tape over his mouth.

He remains defiant. "It is a writer's glorious job to criticise his society," he said, adding with a grin that the state broadcaster was his benchmark for reform.

"China needs more Li Chengpengs. But one day if CCTV starts criticising the government, then I can go back to writing poetry."