A top official at the centre of the biggest political scandal in China in decades has resigned from his parliamentary post, state press said Saturday.

The Chongqing municipal People's Congress accepted the resignation of Wang Lijun from the National People's Congress on June 26, Xinhua news agency said, citing a statement from the NPC.

Wang launched the downfall of his former boss Bo Xilai when he fled to a US consulate in February, seeking asylum after reportedly confronting the powerful Bo with information related to the murder of a British man.

Bo was subsequently stripped of his post as Chongqing's Communist Party head and placed under investigation for corruption, while his wife Gu Kailai, was detained for suspected involvement in the murder of businessman Neil Heywood.

Wang reportedly feared for his life and had fled from Bo's wrath by escaping to the consulate.

Bo, a charismatic leader and the son of a leading revolutionary, had been widely expected to be named to the party's nine-member Politburo standing committee -- the nation's highest ruling body -- during a 10-yearly leadership transition later this year.

His dismissal has been seen as the biggest political scandal to hit China in decades and has reportedly brought turmoil to the leadership transition.

Wang's resignation from the NPC could mean that he could be arrested and his case sent to the state judiciary for trial, Chinese lawyer, Liu Xiaoyuan, who has followed the case, told AFP.

As a delegate to the NPC, Wang could only be arrested upon parliamentary approval, he said.

Overseas Chinese news reports said Wang could be facing charges of treason for fleeing to the US consulate or for leaking state secrets for handing over documents concerning his former boss Bo.

Wang's resignation could also mean his situation is not serious and he could be facing internal party punishment, Liu said.

Xinhua provided no other information on the case, including whether the ruling Communist Party's internal investigative body would hand Wang's case over to the state judiciary.

Both Bo and his wife remain under internal party investigation.

Only days before his flight to the consulate, Bo had sacked Wang as Chongqing police chief, where he had headed a popular crackdown on organised crime.