HANOI - TWO foreign tourists died and seven others were injured when their tourist boat overturned during heavy winds on Vietnam's picturesque Halong Bay, police said on Friday.

A local guide also died in the Thursday evening accident and a Vietnamese tourist was still missing, said Pham Van Truong, an immigration police officer in Quang Ninh province.

'We are trying to identify the nationalities of these two foreigners but it will take us time because there were no documents left on their bodies,' Mr Truong said.

Police recovered the bodies of three victims on Friday morning and were still searching for the missing Vietnamese, the officer said.

Seven injured tourists from Australia, France and the United States were treated at nearby Bay Chay Hospital but were released about midday Friday, said Vu Xuan Dien, the hospital's director.

The boat was carrying 32 people - 14 foreigners, 10 Vietnamese tourists, the guide and seven crewmen, the policeman said.

He added that the accident may have been caused by violent winds that occurred while they were at sea.

Halong Bay, located in the Gulf of Tonkin about 160 kilometres east of the capital Hanoi, was declared a UNESCO World Heritage site in 1994.

Its 1,600 islands and islets form a spectacular seascape of mostly uninhabited limestone pillars made famous by the 1992 French movie 'Indochine.' Numerous tourist boats that ply the waters of the bay offer sleeping and dining facilities.

Last year 2.65 million tourists, including 1.71 million foreigners, visited Halong Bay, according to the provincial tourism department.