A Beijing blogger has refused to hand over further evidence related to a sex scandal that has already claimed the careers of 11 Chongqing officials.

Zhu Ruifeng claims to have sex tapes featuring other high-ranking officials but said on Tuesday he will protect the identity of his source.

The freelance journalist declined a request from Chongqing police for the footage when he met with two officers in Beijing on Monday.

Chongqing authorities are investigating the scandal and Beijing police are providing assistance, said Wang Wenjie, a spokesman for the capital's public security bureau.

Zhu, who runs jdwsy.com, is credited with exposing the sex scandal.

Police said they believe the blogger obtained the tape from Xu Sheqin, a suspect in an extortion scam allegedly masterminded by Xiao Ye, who is alleged to have used young women to seduce officials and secretly filmed them for blackmail purposes.

Zhu posted the video of Lei Zhengfu, former Party chief of Chongqing's Beibei district, on the Internet on Nov 20. Lei was removed from his posts 63 hours later.

In an interview on micro-blogging website Sina Weibo on Tuesday, Zhu said he decided to post that video first because Lei is easily recognizable.

Despite authorities sacking 10 officials in addition to Lei after busting the network led by Xiao, Zhu claimed he still has sex tapes of even higher-ranking officials.

He told Sina Weibo he obtained the footage from a Chongqing police officer and has vowed to protect his identity.

Cao Yin contributed to this story.

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