BANGKOK: An overcrowded tourist ferry capsized and sank near a popular Thai seaside town on Sunday, killing six tourists, including two Russians and a Chinese, police said.

The rest of the roughly 200 people aboard were rescued.

The double-decker ferry, carrying Thai and foreign tourists, left Lan island for the 30-minute trip to the resort town of Pattaya on Sunday evening, said police Col. Suwan Cheawnavinthavat.

Shortly after the boat departed, an engine problem sent the passengers on the first deck rushing to the second floor, causing the ferry to flip on its side and eventually sink.

''Witnesses said there were neither enough tubes nor life vests on the ferry. Some of those who cannot swim had to cling onto coolers or ice containers until rescuers came,'' Suwan said by phone.

He said the foreigners who died were a Russian man, a Russian woman and a Chinese man.

Three Thais, two women and a man, also were killed.

The rest of the passengers were rescued, including a 12-year-old Russian boy who was in intensive care at a hospital.

None of the others were hospitalised.

Suwan said the ferry was operating over its capacity of about 130 to 150 passengers.

He said police were looking for the ferry driver to investigate the cause of the accident.

Pattaya, which is about 100 kilometers southeast of Bangkok, has had several fatal boat accidents this year. Last month, an Indian tourist celebrating her wedding anniversary was killed in a parasailing accident off the town's coast.

In August, two Chinese tourists were killed in a speed boat accident near Pattaya's main pier.

Lan island is a popular daytrip destination among tourists near Pattaya.