China's purged Communist Party leader Zhao Ziyang has died at the age of 85, after suffering a series of strokes.
Zhao had not been seen since his appeal to the 1989 protesters
He died in a deep coma at a Beijing hospital at 0701 on Monday (2301 GMT Sunday), surrounded by his family.
Zhao had been under house arrest since the crushing of pro-democracy protests in Tiananmen Square in 1989.
Security has been tightened in the square in recent days, apparently amid fears that Zhao's death might spark off new reformist demonstrations.
Zhao pressed forward with bold economic reforms while in office, but he was removed after he opposed using military force against the demonstrators in 1989.
He was never again seen in public after 19 May 1989, when he went to the square and made a tearful appeal for demonstrators to leave.
The BBC's Louisa Lim says many will remember him as a symbol of thwarted political reform.
Hours after his death, Zhao's former secretary issued a statement attacking the Chinese authorities.
Bao Tong, who spent seven years in prison and now lives under government surveillance, said Zhao's isolation was a "showcase of shame" for Chinese justice and the Communist Party.
"The fate of Zhao Ziyang is also a chilling reminder of other injustices that are on the consciences of those who are still powerful," he said.
1989 TIANANMEN EVENTS
15 April: Reformist leader Hu Yaobang dies
22 April: Hu's memorial service. Thousands call for faster reforms
13 May: Students begin hunger strike as power struggle grips Communist party
15 May: Soviet leader Mikhail Gorbachev visits China
19 May: Zhao makes tearful appeal to students to leave
20 May: Martial law declared in Beijing
3-4 June: Security forces clear the square, killing hundreds
Reacting to Zhao's death, Japanese Prime Minister Junichiro Koizumi called for China to make "efforts for democratisation".
High-profile dissident Wang Dan, who helped lead the Tiananmen protests, said Zhao represented "Chinese Communist Party members with a conscience".
He showed that "the Communist Party is a bad political organisation, but not every Communist Party member is a bad person", he said.
Zhao's daughter Wang Yannan said Zhao died "peacefully", adding: "He is free at last."
Zhao's son Liang Fang told Reuters news agency that "national leaders" visited Zhao in hospital before his death.
It was "not convenient" to reveal their identities, Mr Liang said.
China's government has issued just a brief statement, confirming Zhao's death.
"Comrade Zhao had long suffered from multiple diseases affecting his respiratory and cardiovascular systems, and had been hospitalised for medical treatment for several times," the official Xinhua news agency reported.
Zhao had been under house arrest since the 1989 protests
"His conditions worsened recently, and he passed away Monday after failing to respond to all emergency treatment."
A few postings appeared on China-based websites, many mourning Zhao and some criticising the Chinese authorities. However, most postings were taken down as news of his death spread.
Zhao is understood to have fallen into a coma on Friday.
China almost never commented on Zhao, who had been expected to succeed Deng Xiaoping as the country's paramount leader, until Zhao was removed from office.
The deaths of other liberal leaders in China have tapped latent public frustration at the country's slow pace of democratic reform.
Protests flared when former Premier Zhou Enlai died in 1976, and pro-reform party leader Hu Yaobang's death in 1989 sparked the Tiananmen Square protests that ended Zhao's political era.