FBI and Bermuda Police investigators have boarded the cruise ship Norwegian Dawn in Dockyard in Bermuda to investigate the death of a passenger who fell overboard while the ship was on its way to the Island.

Family members are fearing the worst for mother-of-two Mindy Jordan, of New Jersey — who plunged from the Norwegian Dawn 45 miles northeast of Atlantic City on Sunday evening .

Her sister Julie August was reported by the New Jersey media as "expecting the worst", saying: "It's been such a long time."

The US Coast Guard conducted a helicopter search over about 60 square miles until the early hours of Monday. It will only resume the search if more can be found out about Ms Jordan's location.

The FBI is reported to be investigating, while the Coast Guard says a marine casualty probe is also taking place. Ms Jordan's family say they do not accept allegations the 46-year-old had been "clowning around". Ms August is quoted saying: "My sister is a professional. She's a nurse and a mother. This is not somebody who's going to be jumping up on a rail."

The incident happened just hours after the ship pulled out of New York City for a one-week cruise to Bermuda. It is scheduled to reach the Island today.

Norwegian Cruise Lines said the woman was apparently trying to climb between balconies on a cruise ship when she fell overboard.