Around 50 people are known to have died in a ferry disaster off the coast of Bahrain in the Gulf. A tourist boat sank during a dinner cruise with more than 130 people on board. There is no indication of the cause, but officials say a terrorist attack seems very unlikely.US helicopters and divers have joined the rescue operation. Bahrain, a tiny island on the western side of the Gulf, is the home of the US fifth fleet. The sinking happened about one and a half kilometres from land. The passengers are reported to have been a mix of Bahrainis, nationals of other Gulf Arab states, Europeans, and Asians. It is thought around 25 Britons were on the boat. The interior ministry says most of those on board were employed by a Bahrain-based company. Officials have been visiting survivors in hospital. Reports have come in that some people who had signed up for the cruise decided not to get on, believing the ship was overcrowded and ill-equipped. The weather was apparently perfect when the vessel capsized.