The judge who presided over the trial of Wang Lijun, the former right-hand man of disgraced politician Bo Xilai, has been removed from his post, authorities said, stoking speculation over the significance of the move.

Wang was the chief of police in the southwestern metropolis of Chongqing when he fled to a US consulate in Chengdu, allegedly to seek asylum, blowing open China's biggest political scandal in years.

At his trial, where Zhong Erpu was the chief judge, Wang was convicted of corruption, defection and other crimes and sentenced to 15 years in prison.

Zhong was "relieved" as deputy director of the Intermediate People's Court of Chengdu, in Sichuan province, the ruling Communist Party's powerful organisation department said in a brief statement.

It did not give a reason for Zhong's removal.

Bo was a populist but divisive figure whose "red revival" policies raised worries in some quarters over his leftist bent. His fall exposed deep divisions within the party.

The scandal, which saw Bo's wife convicted of murdering a British businessman, emerged ahead of a once-a-decade leadership transition last year, in which Bo had been considered a candidate for the Politburo Standing Committee -- China's most powerful body.

Zhong himself said the removal was due to his retirement, according to Thursday's 21st Century Business Herald newspaper.

But he is said to have been born in 1965, which would put him in his late forties, and rumours raged over the possible political manoeuvrings behind the decision, particularly as Bo's trial is expected in the near future following his indictment last month.

One theory was that Zhong may have done something wrong in Wang's case and the authorities announced his removal now to warn Bo's judges, suggested a blogger on the overseas Chinese website dwnews.com, which often carries unsourced rumours.

Another possibility, the blogger said, was that he had been implicated in the corruption case of Li Chuncheng, former deputy party chief of Sichuan, who state media said in December had been sacked.

Chinese officials can be "relieved" from their position for reasons including promotion or demotion, leave for study for over a year, health problems and retirement. The word used in the statement, posted Tuesday, does not necessarily imply punishment.