Youssif al-Ghatam, the coastguard commander, told a news conference that 63 people had so far been rescued.

He said most of those on board the boat were of Asian origin, but passengers also included Europeans and Arabs.

The death toll from different nations was: India 17, Britain 13, Pakistan five, South Africa four, the Philippines three, Singapore two, Germany one and Ireland one, an Interior Ministry official said.

Officials said the boat had been hired by a local contracting company for a cruise and there were indications it was carrying many more passengers than it was licensed to.

Weather conditions at the time were said to be near perfect.

Organisers said around 150 people had signed up for a dinner cruise but around 130 were believed to have been on board when the boat sank on Thursday night, around 1.5km off the coast.

One witness said the boat capsized when too many passengers gathered on one end of the 100-metre long vessel.

Attack ruled out

US and Bahraini officials said there was no indication that the sinking was the result of an attack.

"Up to this moment, it appears totally unlikely," Ghatam said.

Sheikh Rashid bin Abdulla Al Khalifa, the Bahraini interior minister, earlier said most of the ferry's passengers were employees of a Bahrain-based company.

Television footage showed survivors in shock and their hair still wet, squatting on the floor of a hospital.

A US Navy spokesman said divers and small Navy vessels were helping in the rescue operations.