HONG KONG (AFP) - Hong Kong police on Saturday discovered two corpses in a posh apartment building, one of which was found decaying in a large suitcase, and have arrested a foreign man.

Police were called to the scene in Wanchai district early Saturday and initially found a woman with knife wounds in the living room.

"There was a female that was unconscious, with knife injuries and was naked," assistant district commander Wan Siu Hung told reporters.

Wan said the victim, who was certified dead, was between 25 and 30 and the cause of death was thought to be from a cut on her throat.

Police said they arrested a 29-year-old foreign man who lives in the apartment and described the first victim as a foreigner. Police could not provide their nationalities when contacted by AFP.

"We found one more body - the corpse was placed in the apartment's balcony," the spokesman told reporters later Saturday.

"From what we can see it was intentionally hidden because it was put in a travel suitcase," he said, describing the suitcase as one metre (three feet) in length and half a metre in width and height.

"This body belonged to a person who has passed away for quite some time," the he said, adding that maggots were found in the corpse.

The gruesome case is unusual in Hong Kong, which has very low levels of violent crime.

According to police statistics, the city of seven million saw 14 cases of homicide in the first half of the year.

In recent years Hong Kong was gripped by a lurid case dubbed the "Milkshake Murder" in which American housewife Nancy Kissel killed her banker husband.

Kissel, now serving a life sentence, was convicted of drugging her husband - a senior executive at US bank Merrill Lynch - with a sedative-laced strawberry drink before clubbing him to death with a lead ornament at their luxury home in 2003.