(Recasts with death toll, new figure of missing personnel and updated overall number of crew) LONDON, April 12 (Reuters) - Three Norwegian crew members died and another five were missing after their tugboat capsized in the North Sea on Thursday, British coast guards said. A further seven personnel were rescued from the Bourbon Dolphin, a Norwegian anchor-handling supply tug, which capsized 75 miles (121 km) north of Scotland's Shetland Islands, a spokeswoman for the Maritime and Coastguard Agency said. As night set in, a rescue operation involving two helicopters and three nearby vessels was scaling down but a naval diving unit remained on the scene with divers planning to continue the search, said Sophie Turner. "In the morning the helicopter will be back on the scene," Turner said, while warning it was unlikely the missing crew would survive until then in the cold sea waters. It would be a "search and recovery operation tomorrow not a search and rescue", she said. The North Sea near Scotland sees heavy traffic from vessels supplying off shore oil rigs. Waters there are deadly cold this time of year, but weather in the area was described as good. Sea rescue experts said crew in the water could survive for a few hours, but only if they were wearing survival suits designed to keep them warm. Turner said it was not yet known why the boat capsized.
