Political observers were also intrigued by the sensitive timing of the detention, pointing to its uncanny resemblance to the fall of the former Shanghai mayor Chen Liangyu six years ago, in the lead-up to the previous party congress.

Chen's fall from grace, as a result of his involvement in the corruption case of a Shanghai tycoon, was widely seen as having reshaped the political landscape on the mainland, tipping the balance of power in a struggle between factions loyal to President Hu Jintao and his predecessor Jiang Zemin .

Like the removal of Chen in 2006, Wang's detention will have political ramifications and looks set to usher in a period of intense jockeying for position and power in the run-up to the next leadership transition at the party congress later this year.

Analysts said that if confirmed, rumours that Wang, 52, had attempted to turn Bo, 63, in to the top disciplinary watchdog would be devastating news for Bo, the son of a party elder, and a top contender for a seat on the Politburo Standing Committee.

Zhang Ming, from Renmin University in Beijing, said he believed the rumours were largely true. 'Although no one expected the day to come so quickly, it will virtually mean the end of Bo's political future and the bankruptcy of the so-called Chongqing model,' he said.

Bo has earned notoriety for his crusade against organised crime, a controversial campaign to resurrect Maoist revolutionary culture and his over-the-top showmanship.

Zhang said Bo's potential involvement in Wang's case would have greater impact than the fall of Chen, as China was facing a full-fledged leftist backlash featuring Bo's ultra-conservative ideas.

Zhang and other analysts also said that despite Bo's high-profile manoeuvring over the past few years, the gang-busting Chongqing party boss had failed to get endorsement from top leaders, including Hu and Premier Wen Jiabao .

Professor Yuan Weishi, a historian at Guangzhou's Sun Yat-sen University, said both Bo and Wang would be held accountable for their controversial anti-triad crusade, which was widely criticised by intellectuals for allegedly riding roughshod over the rule of law.

'It seems certain that Wang has got himself into major trouble and once the anti-triad campaign is allowed to be reviewed, it will be a decisive blow to Bo's career,' Yuan said.

While the re-examination of Bo's use of extrajudicial administrative powers to tackle lawlessness was good news for the nation, Yuan said it was too early to tell what impact it would have on the leadership reshuffle: 'It remains a fact in China that personnel decisions may be subject to change until the very last minute.'

Dr Kerry Brown, a senior fellow with the London-based Chatham House, expressed doubt over rumours that Hu and his supporters were behind the move against Wang.

'I don't see why Hu Jintao or any of the leadership would undertake such a risky move as going for someone like Wang at a sensitive time like this,' he said. 'I'd have thought this was the last thing the leadership in Beijing wanted in a difficult year when all they want is a successful transition without incident.'