Nadeem Razaq, 24, who has lived in Hong Kong since the age of two, did not enter any plea at a court hearing yesterday.

He was returned to police custody, with the case adjourned until next Tuesday to allow further investigation, a prosecutor said.

Hong Kong police arrested Razaq on Tuesday after four prostitutes were killed over four days in different parts of the city, the South China Morning Post reported yesterday.

The four women, who advertised their services on two Hong Kong websites, were found dead in their 'one-woman-brothel' apartments.

But the fourth might be a separate case as the woman was found dead in the Hong Kong Island district of North Point on Monday afternoon.

The other three were found killed in Yuen Long and Tai Po in suburban New Territories on Friday, Saturday and early on Monday, reports here said.

The fourth victim was aged 27 while the other three were between 30 and 35 years old.

The first three women were strangled and battered to death and their flats were ransacked and valuables taken, the police said.

Officers said that when they arrested Razaq upon his repatriation from Macau on Tuesday, mobile phones belonging to two of the victims were in his possession.

According to Hong Kong's Chinese media, local police sought the help of their Macau counterparts after they intercepted a call made from the missing mobile phone of one of the prostitutes.

The caller was Razaq, who asked one of his two elder brothers for money, reported the Sing Tao Daily.

His Pakistani identity matched the suspicion that the killer was from South Asia, as suggested by images captured on security cameras at the brothels, said the newspaper.

Macau police moved in on Razaq when he turned up at a jetty to meet his brother on Tuesday.

From sources who knew the suspect, Hong Kong media put together the picture of a solitary man who moved to the territory from Pakistan at a young age with his family and is a Hong Kong identity card holder.

Razaq speaks Cantonese fluently and is known to be fond of gambling.

He has had brushes with the law before over petty crimes. But reports said that what ruined him was his gambling habit, which landed him with huge debts and caused him to lose his job recently in the second-hand car firm of one of his brothers after he misappropriated company funds.

In desperation, Razaq went on a killing spree, said the reports.

He could face life in jail if convicted.

Yesterday another newspaper, Wen Wei Po, said that the police are investigating the husband of the fourth murder victim, a recent immigrant from China. They are said to believe that the husband copied the first three murders to cover up his crime.

The suspect has fled to the mainland, the newspaper quoted a police source as saying.