Tatiana Tsimfer, 30, and Liubov Svirkova, 25, were found dead in their beach chairs at about 5am, along with five spent 9mm cartridges, said Colonel Sutin Trappuang, superintendent of the Pattaya police station.

 Footprints from canvas shoes left at the scene were believed to belong to the attacker, he said, adding that the autopsies would be carried out in Bangkok.

A security guard at a nearby resort told police he heard several gunshots and saw a Thai man in his 20s run from the beach and speed away on a motorcycle. The guard rushed to the beach and found the two bodies.

Lt-General Asawin Kwanmuang, commissioner of Provincial Police Region 2, declined to speculate on the motive, but said the killer apparently did not want to rob the victims but to take their lives.

Police dispatched 12 special units to trace the victims' final hours.

Since both still had their makeup on, they might have visited night entertainment spots, so police also called in potential witnesses from South Pattaya's famous Walking Street zone.

Police also suspect the attacker might have been stalking the women to the murder scene, he said.

The two women arrived on February 16 as part of a tour group with four other women and

were scheduled to leave next Saturday.

The victims' four friends, who were away on a trip to Kanchanaburi, will soon be summoned to determine whether there were any conflicts that could be a possible motive, he said.

Pattaya, about 110 kilometres southeast of Bangkok, is known for its beaches, thriving sex industry and high crime rate.