An ex-police chief whose flight to a US consulate triggered the biggest scandal to rock China's ruling Communist party in years was put on trial in a closed session Monday, his lawyer said.

Wang Lijun, former right-hand man of disgraced politician Bo Xilai, faces charges including defection, abuse of power, bribery and bending the law for selfish ends.

"Wang Lijun's trial started this morning," defence lawyer Wang Yuncai told AFP, refusing to give any details about the content of the hearing.

Media and the public were barred from the first day of the proceedings in the southwestern city of Chengdu, but she said that Tuesday's session would be "open".

Wang fled to the US consulate in the city in February, setting in motion a political crisis which exposed deep divisions within the upper echelons of Chinese politics ahead of a generational transfer of power.

The scandal led to the sacking of Bo, one of China's most high-profile political figures, and the conviction of his wife Gu Kailai for the murder of a British businessman.

Wang, 52, was drafted in by Bo, then the top Communist party official in the sprawling metropolis of Chongqing, to mastermind a crackdown on the local mafia which Bo hoped would propel him into the top ranks of Chinese politics.

The campaign led to thousands of arrests and prompted allegations of widespread torture and human rights abuses by Chongqing police.

But relations between Bo and Wang turned sour early this year, months after British businessman Neil Heywood, a close associate of Bo's family, was found dead in a Chongqing hotel room.

Wang fled to the US consulate after an apparent dispute with the politician, reportedly telling officials that Bo's wife had murdered Heywood.

Gu was convicted of Heywood's murder by a Chinese court last month and given a suspended death sentence -- normally commuted to life imprisonment -- after a short trial which was thought to be subject to heavy political interference.

A spokeswoman for the Chengdu Intermediate People's Court confirmed Wang's open trial will start Tuesday morning.

The proceedings will be closely watched for clues about the fate of Bo, who has not been seen in public for months and is currently believed to be under house arrest.

But analysts said that because of the case's political sensitivity it would be carefully stage-managed by party officials.

"It's a political arrangement, rather than an independent judicial trial," City University of Hong Kong political analyst Joseph Cheng told AFP. "The verdict will relate to a political agreement amongst top Chinese leaders to limit the fallout from the Bo Xilai case."

One key issue is whether the official account of the trial will mention allegations Wang carried out extensive phone tapping of senior officials who visited Chongqing, even recording a conversation involving President Hu Jintao.

"Something like this certainly could not have happened without Wang's boss, ie Bo, authorising or knowing," Steve Tsang, professor of contemporary Chinese studies at the University of Nottingham, said in emailed comments.

"If there is no mention of Bo it would imply that the leadership still cannot agree on what to do with him."

Outside the white-tiled Chengdu courthouse, a group of retired men standing next to a notice board for trial verdicts doubted the truth about political machinations in Chongqing would be revealed.

"The result will be posted up here, but it will just be words, there's no way ordinary people like us will know what happened between Wang and Bo," said one, declining to give his name because of the police presence around the building.