The Chinese government has said that former Communist Party leader Zhao Ziyang is ill in hospital, but stable.
Mr Zhao has not been seen since his appeal to the 1989 protesters
The official statement follows reports at the weekend that he had died.
Mr Zhao, 85, has been under house arrest since the pro-democracy protests in Tiananmen Square in 1989, which he was accused of sympathising with.
Correspondents say the Chinese leadership is worried Mr Zhao's death could spark renewed calls for reform.
Many Chinese still view him as a symbol of democratic ideals.
Chinese Foreign Ministry spokesman Kong Quan told reporters on Tuesday: "Zhao Ziyang is an old man who is over 80. He fell ill, but after attentive treatment, his condition is currently stable."
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 Ziyang makes tearful appeal to students to leave
20 May - Martial law declared in Beijing
3-4 June - Security forces clear the square, killing hundreds
"Overseas media reports that Zhao Ziyang died on 8 January are totally untrue," the spokesman said.
Mr Zhao is suffering from respiratory problems, according to Hong Kong-based rights activist Frank Lu, quoting Mr Zhao's daughter in Beijing.
Wang Yannan told Mr Lu that her father had been in hospital for about a month, and was "not in danger", but other unnamed sources told Reuters news agency that Mr Zhao's state was "not good".
China almost never comments on Mr Zhao, who was expected to succeed Deng Xiaoping as the country's paramount leader, until his removal from office at the height of the Tiananmen protests.
But the administration would be anxious to assure the public that he had not died. The deaths of other liberal leaders in China have tapped latent public frustration at the country's slow pace of democratic reform.
When former Premier Zhou Enlai died in 1976, and pro-reform party leader Hu Yaobang died in 1989, protesters massed in Tiananmen Square.