He is expected to be jailed for several years for accepting bribes and expensive gifts and for dereliction of duties.

Chen's younger son, Chen Xiaotong, would also be brought to court, sources said.

Beijing officials insisted that Chen Xitong would not receive any special treatment when his case was brought to court.

He was sacked in April 1995 after his protege, vice-mayor Wang Baosen, committed suicide after being investigated over a corruption scandal involving more than HK$280 million.

Chen was ousted from the Politburo in September 1995 but he remains a Communist Party member.

His mistress, He Ping, is still on the run.

'Chen's mistress is now in the United States.

'Investigators believe that she has transferred around 200 million yuan [HK$186.6 million] out of China,' sources said.

Officials hope US authorities can help to extradite her.

During the investigation 50 huge photographs of He posing nude were found in Chen's villa, a source said.

The pictures were developed in Hong Kong and some had been pasted on the walls.

Investigators searching the villa also found gold taps and door handles which had been ordered and made in Hong Kong.

Gold cassette discs featuring Chen and He singing pornographic songs were also found.

The party's disciplinary investigation against Chen has dragged on for a long time and there are increasing demands being made for an explanation from the authorities.

Sources said Chen had been under house arrest during the investigation.

'The party is determined to have the case dealt with before the 15th Party Congress starts in the autumn,' sources said.

Authorities hope such a move can show the party's determination to take tough action against high-level corruption.