Hong Kong police have arrested a Pakistani as a suspect linked to the killings of four sex workers in the city in three days.

The 24-year-old man was arrested early today in Hong Kong upon his return from Macau, People's Daily reported on its website today.

The four killings occurred between March 14 and yesterday. Three took place in the New Territories districts of Tai Po and Yuen Long. The other happened in the Hong Kong Island district of North Point, according to statements on the Hong Kong Police Department website.

Police traced the Pakistani after they discovered that someone had used the mobile phone of Qiqi, one of the killed prostitutes, the report cited the police authority as saying.

Police recovered two mobile phones belonging to two of the victims from the Pakistani man when he was arrested, Superintendent Steve Li said, according to media reports.

But the Pakistani has only admitted to the killings of the three sex workers in the New Territories, leaving the death of 27-year-old prostitute Tan Shaofen unclear, the People's Daily report said.

Tan was found naked in her apartment's bathtub and was strangled with a shower hose yesterday.

The four women, aging from 27 to 35, had also been robbed.

One of the women was found with a swollen forehead and injured jaw. The other two did not have obvious external wounds.

Police said Hong Kong Customs has a record showing the Pakistani left for Macau on Sunday afternoon, which means he could not have been involved in Tan's death.

Police said Tan's killer is still at large and they suspect that it may be a copycat case.

The Pakistani will soon be on trial for murder, the report said.

Police are still probing into his motive for the killings, the report said.

(Shanghai Daily, March 18, 2008)