A former Chinese police chief whose visit to a US consulate sparked rumours he was trying to defect flew to Beijing with a top state security officer after meeting American officials in southwest China.

Wang Lijun, who has close links to a high-profile contender to join China's top decision-making body, flew first class from Chengdu to Beijing on February 8, according to a travel website authorised to show passenger flight details.

Qiu Jin, who is the deputy head of China's State Security Ministry, also had first class seat on the same flight. The website Travelsky, which is backed by China's aviation regulator, shows the tickets were used.

Wang, vice mayor and former police chief of Chongqing, is famed as one of China's top graft-busters after leading a crackdown that led to scores of senior officials being jailed in the southwestern city of 30 million people.

He has close links with Chongqing's Communist Party secretary Bo Xilai, who is the son of a Chinese revolutionary and is widely expected to be promoted to a top party post in a 10-yearly leadership transition that begins this year.

Wang was dismissed as Chongqing police chief last week, and on Wednesday Chinese websites buzzed with rumours he had sought asylum at the US consulate in the southwestern city of Chengdu.

The US embassy in Beijing confirmed Wang's visit to the consulate this week but declined to comment on the rumours he had sought asylum, saying only that he had gone there for a meeting and left "of his own volition".

China's official Xinhua news agency said authorities were "investigating the incident".

Analysts said the confirmation of the visit would further fuel speculation surrounding Wang and Bo, and said it could hamper Bo's chances of promotion to the nine-member Politburo Standing Committee, China's top decision-making body.