The Beijing mayor was purged in 1995, and three years later sentenced to 16 years jail on corruption charges. Along with former Shanghai party secretary Chen Liangyu and former Chongqing party secretary Bo Xilai, he was one of the highest-ranking officials to have faced such charges. 

Instead of Babaoshan, Chen's funeral was held in Changping, a suburb northwest of the capital, where he began his career in the 1970s. The family's wishes for the national anthem to be played and the coffin wrapped in the Communist Party's red hammer and sickle flag were also refused, the source said.

Chen had been stripped of his party membership in 1997. The terse Xinhua statement announcing his death did not refer to him as "comrade" - a title reserved for party members.

Contrary to protocol for former high-ranking officials, no contemporary or current leading representatives of the national or the Beijing municipal leadership attended the funeral.

The source spoke of a heavy police presence at the Changping funeral parlour, with cell phone signals being deactivated and a ban on taking of photos. More than 1,000 onlookers gathered outside the parlour, the source said.

Chen's wife was too ill to attend the funeral. Currently undergoing treatment in hospital, the source said she has not yet been informed of his death. Both sons did not attend the funeral.

Another source, who had been in contact with Chen in the last few months of his life, told the Poston condition of anonymity that Chen was very bitter towards Jiang Zemin until the very end.

According to the source, Chen repeatedly told those around him that Jiang had framed him and had him convicted on trumped up charges. Chen expressed a strong wish to outlive Jiang, who is 87 this year.

Chen has never admitted to corruption charges, Yao Jianfu, a senior scholar close to Chen, had told the Post last year. 

"I was never handcuffed and never signed any confession letter," Chen says in Conversations with Chen Xitong, a book written by Yao and published by Hong Kong's New Century Media last year.

After serving eight years of a 16-year sentence in a Changping prison, Chen was admitted to a hospital in 2004 and granted medical parole in 2006. He spent the last years of his life under guard in Beijing.

Chen's doctors at the General Military Hospital of Beijing tried hard, at the request of his family, to sustain his life beyond August, when Chen would have served out his 16-year sentence.

"He wanted desperately to live to the day when he would be a completely free man," said the source.