The second of five "missing" Hong Kong booksellers who was detained on the mainland returned to the city on Sunday, authorities said, in a case that has triggered fears of increasing Chinese interference in the semi-autonomous region.

Cheung Chi Ping's return to Hong Kong comes a week after he appeared on Chinese television with four of his colleagues, where some admitted to smuggling illicit literature into the mainland. Cheung had been missing since October.

"Hong Kong Police Force met with Cheung Chi Ping who has returned to Hong Kong from the mainland," the statement issued by Hong Kong's police said.

During the meeting, Cheung requested to have his missing persons case closed and requested his case to be dropped.

"He refused to disclose other details," the statement added.

His return to Hong Kong follows fellow bookseller Lui Por's arrival in the city Friday. Chinese media said last week Cheung, Lui and colleague Lam Wing Kee would all be released on bail. However, authorities have not been able to confirm when Lam will return to Hong Kong.

The five booksellers from Hong Kong's Mighty Current publishing house, known for its salacious titles critical of Beijing, went missing last year, only to turn up in mainland China.

One who apparently disappeared from Hong Kong, Lee Bo, appeared on television last week and insisted he had not been abducted by mainland authorities.

In the Phoenix TV interview, Lee said he had "resorted to illegal immigration" to get to the mainland as he did not want to draw attention to his visit and that he made the trip so he could cooperate in an investigation.

The other four booksellers, who are under criminal investigation on the mainland, also appeared on Phoenix last week, admitting to smuggling illicit books into China in sombre, sometimes tearful interviews.

The cases have heightened fears of increasing mainland Chinese interference in Hong Kong and sparked international condemnation.

Britain had said the disappearance of Lee, a British citizen, was a "serious breach" of an agreement signed with Beijing before the city was handed back to China in 1997 which protects its freedoms for 50 years.