Image caption The downfall of Bo Xilai (left) was triggered when his police chief Wang Lijun (right) fled to a US consulate

China's state-run news agency has linked fallen politician Bo Xilai to a criminal act for the first time, alleging he knew his wife was suspected of murdering a British businessman.

Xinhua quoted witnesses at the trial of his former right-hand man, Wang Lijun, suggesting that Mr Wang had tried to tell him about his suspicions.

Mr Wang was "angrily rebuked and had his ears boxed", Xinhua reports.

Mr Bo's downfall exposed the biggest political crisis in China for years.

His wife, Gu Kailai, was found guilty in August of murdering British businessman Neil Heywood. She was given a suspended death sentence.

Wang Lijun was the police chief and deputy mayor in Chongqing, where Bo Xilai was Communist Party chief until the scandal erupted.

The 52-year-old Mr Wang began his career in law enforcement in the Inner Mongolia Region in 1984 and moved to the south-western city of Chongqing in 2008.

'Secret confession'

Earlier this week he pleaded guilty to defection, abuse of power and bribe-taking charges during a two-day trial in the nearby city of Chengdu. A verdict is awaited.

Analysis The figure of Bo Xilai has loomed large over the murder of the British businessman Neil Heywood. Mr Bo's wife has already been found guilty of carrying it out, and it was initially covered up by officers under his control in the city of Chongqing. But although he's been suspended from his position on the country's powerful politburo, state media have not mentioned him in connection with the case, until now. The release of the new details from his police chief's trial may be an indication that Bo Xilai will also face criminal charges. If so, it would complete the fall from grace of one of China's most powerful men and prolong a scandal that has tested the Communist Party at a sensitive time as it prepares for a change in the top leadership later this year.

In its official published account of his trial, Xinhua reports that Mr Wang spoke with Gu Kailai at midnight on the night of the murder of Mr Heywood, and again the following day at her residence. He secretly recorded her confession.

"I told him in detail about how I met and poisoned Neil on the night of 13 November. He told me not to be bothered by the case, which would have nothing to do with me in the future," Gu Kailai is quoted as saying while testifying at her trial, the state news agency reports.

On 15 November, after My Heywood was found dead, Wang Lijun instructed the deputy chief of Chongqing's Public Security bureau, a close personal friend of Gu Kailai, to handle the case without telling anyone else that he had evidence of her involvement.

In late January, Mr Wang tried to tell "the Chongqing party committee's main responsible person at the time" about his suspicions about Gu, says Xinhua, without naming Mr Bo.

'Safety threat'

A day later he was slapped in the face and "angrily rebuked" by the official, Xinhua reports.

According to an official present, who was quoted by Xinhua, "the conflict was made public after Wang Lijun was slapped".

TIMELINE: BO XILAI SCANDAL 6 Feb: Chongqing police chief Wang Lijun flees to the US consulate in Chengdu

Chongqing police chief Wang Lijun flees to the US consulate in Chengdu 15 Mar: Bo Xilai is removed from his post in Chongqing

Bo Xilai is removed from his post in Chongqing 20 Mar: Rumours suggest Mr Bo could be linked to the death of British businessman Neil Heywood

Rumours suggest Mr Bo could be linked to the death of British businessman Neil Heywood 10 Apr: Mr Bo is suspended from party posts and his wife, Gu Kailai, is investigated over Mr Heywood's death

Mr Bo is suspended from party posts and his wife, Gu Kailai, is investigated over Mr Heywood's death 26 July: Gu and Bo family employee Zhang Xiaojun are charged with killing Mr Heywood

Gu and Bo family employee Zhang Xiaojun are charged with killing Mr Heywood 9 Aug: Gu Kailai goes on trial for murder

Gu Kailai goes on trial for murder 20 Aug: Gu given suspended death sentence

Gu given suspended death sentence 5 Sept : Wang Lijun charged with defection, abuse of power and bribe-taking

: Wang Lijun charged with defection, abuse of power and bribe-taking 17 Sept: Mr Wang's trial starts in secret in Chengdu

Mr Wang's trial starts in secret in Chengdu 18 Sept: Trial ends, verdict awaited

The same day Wang Lijun ordered witnesses to be interviewed again and evidence - including blood extracted from Neil Heywood's heart - to be protected. The file on the case was ordered to be rearranged, Xinhua reports.

"I knew Wang Lijun and Gu Kailai had turned hostile towards each other at that time, otherwise Wang Lijun would not have asked us to rearrange the file," one official, Wang Zhi, is quoted as saying.

As Chongqing Communist Party chief, Mr Bo was tipped for promotion to the top leadership ranks at China's forthcoming leadership congress before his downfall.

Mr Wang's flight to the US consulate in the nearby city of Chengdu in February sparked the events which led to the politician's downfall.

According to the UK Foreign Office, Mr Wang made allegations about Mr Heywood's death while at the US consulate. Shortly afterwards, Mr Bo was removed from his post in Chongqing and suspended from the politburo and Central Committee.

According to Xinhua, Mr Wang "requested the Americans to provide asylum, and wrote an application for political asylum".

He told them he "had received a threat to his personal safety as a result of investigating a case".

Mr Wang spent the night in the consulate but was persuaded to leave a day later. He gave himself up to police and has been in detention since then.

Mr Bo has not been seen in public since the scandal erupted and is said to be under investigation by the party's disciplinary officials.