Four police officers have gone on trial accused of covering up the killing of a British man for which Gu Kailai, the wife of deposed Communist Party official Bo Xilai, has been charged.

The trial in the eastern city of Hefei followed Thursday’s hearing of charges that Gu and an assistant, Zhang Xiaojun, poisoned British citizen Neil Heywood in the southwestern city of Chongqing.

The four senior officers from Chongqing were “suspected of covering up (Gu’s) illegal conduct during the investigation into Neil Heywood’s death” and “bending the law to achieve personal benefit”, the court said before the trial on Friday.

They included Guo Weiguo, the city’s former deputy police chief, and two senior detectives.

The Hong Kong-based South China Morning Post on Thursday quoted anonymous sources as saying that a court in the southwestern city of Chengdu was expected to open the trial of Guo’s former boss, Wang Lijun, next week.

Wang was Chongqing’s hardline police chief and a longtime ally of Bo until he was sacked from his post and fled to the US consulate in Chengdu in February, setting off a scandal that brought down Bo.

It now appears that Wang’s flight was linked to attempts by the other officers, and perhaps Bo, to cover up Heywood’s killing.

According to unconfirmed reports, Wang could be charged with treason.

Thursday’s trial of Gu, 53, was the biggest event so far in what many see as the worst crisis to hit China’s ruling Communist Party since a rift before its 1989 military crackdown on pro-democracy protesters.

Gu did not contest the charges against her, court spokesman Tang Yigan said on Thursday, adding that the court would issue its verdict at a later date.

Bo was once seen as a contender for a top leadership role but he was sacked from his post as Chongqing Communist Party chief in March.

No charges against Bo have been announced but the party said it was investigating him for “serious breaches of discipline”.

Bo had attracted a significant following by “leftists” among the party’s 80 million members, some of whom seek curbs on economic reforms and even a return to the extreme egalitarianism of Mao Zedong.