Investigators have few clues as to a motive behind the killings.

Tatiana Tsimfer, 30, and Liubov Svirkova, 25, were found dead in their beach chairs at about 5am on Saturday.

Five spent 9mm cartridges were recovered from the scene.

Post mortem examinations show one woman was shot six times and the other four times, according to Provincial Police Region 2 commissioner Lt-General Asawin Kwanmuang.

Security cameras captured a "tall man of indistinct nationality" parking a motorcycle at a beachside footpath, running up to the women and shooting them before fleeing.

Police have discounted robbery.

"From the gunman's dress - jeans and boots - we suspect he is a member of a Pattaya teenage gang," Asawin said.

Both the women worked as telephone operators in Vladimir City in Russia and were visiting Thailand with a tour group.

Asawin said the women entered Thailand on February 16. They separated from the group to travel by themselves.

"They probably had nothing to do with the transnational prostitution," Asawin said. "I have no idea what they did during the eight days in Pattaya to lead to their murder."

A counsellor at the Russian Embassy in Bangkok, Vladimir Pronin, met the police yesterday and rejected allegations in local newspapers the women were involved in prostitution.

He expressed concern for Russian tourists in Thailand.

Police set up a temporary command post at a hotel near the scene.

Twelve units have been assigned to the case that police worry might affect tourism at the popular seaside resort.

Pattaya police superintendent Colonel Sutin Trappuang said investigators were looking at prostitution, drugs and sex as motives.

Police are questioning known members of Russian gangs living in Pattaya and people at night entertainment venues on the city's Walking Street.