China put the ex-police chief who set off the Communist party's biggest scandal in years on "public" trial Tuesday, and the court said he did not contest charges including defection and bribery.

But foreign media were barred from the hearing, one day after a closed-door session, highlighting official attempts to control the trial of Wang Lijun -- who the court had said exposed "major violations of the law" by others.

Wang fled to the US consulate in Chengdu in February, setting off a crisis that saw the fall of his patron Bo Xilai and revealed deep divisions in the upper echelons of Chinese politics ahead of a generational transfer of power.

But his co-operation with authorities made him eligible for leniency, both prosecutors and defence said, suggesting he will avoid execution.

Footage shown on state broadcaster CCTV showed Wang sitting on a wooden chair in court Tuesday, looking relaxed and apparently speaking into a microphone.

Police cordoned off the area in front of the courthouse, with dozens of officers visible around its perimeter.

Wang "did not raise an objection" to the facts and charges of defection, abuse of power, bribe-taking or bending the law for selfish ends, said a statement from the court in Chengdu, in southwestern China.

After Tuesday's trial the court said it would announce its decision at a later date, and a guilty verdict is considered almost certain.

The charges could carry the death penalty, but prosecutors said he could be given a lighter sentence because he "made a significant contribution to the resolution of the Gu Kailai murder case", the court statement said, referring to Bo's wife.

Defence lawyer Wang Yuncai also argued for a reduced penalty, saying her client "had a reason to choose to defect and he stopped committing the crime part way through", according to the statement.

The court dealt with the charges of defection and abuse of power in a separate closed hearing because they related to state secrets, it added.

Prosecutors said Wang took bribes of more than three million yuan ($460,000).

The court document made no explicit mention of Bo, who has not been seen in public for months and is believed to be under house arrest, facing investigation by the Communist party for "serious" discipline violations.

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.

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 that was thought to be subject to heavy political interference.

Analysts said before Wang's trial that because of its political sensitivity it would be carefully stage-managed by party officials.

"All we will see is what the party would like us to see," Steve Tsang, professor of contemporary Chinese studies at Britain's University of Nottingham, said in emailed comments.

Not mentioning Bo in the statement, he said, "would imply that the leadership still cannot agree on what to do with him".

City University of Hong Kong political analyst Joseph Cheng told AFP: "It's a political arrangement, rather than an independent judicial trial.

"The verdict will relate to a political agreement amongst top Chinese leaders to limit the fallout from the Bo Xilai case."

The court statement did not mention widely reported allegations that Wang carried out extensive phone tapping of senior officials who visited Chongqing, even recording a conversation involving President Hu Jintao.

It only cited prosecutors saying that Wang had "used technical surveillance methods against many people" and "seriously damaged" China's legal system.