THOUSANDS of passengers travelling on a Southampton based cruise ship could be refused entry into the U.S after an outbreak of a winter vomiting bug.

A total of 30 people are currently confined to their cabins on Cunard's £270m Queen Victoria, which left the city's docks on Monday.

Authorities have warned that the ship will not be allowed to dock in New York if the virus reaches an epidemic rate of 15 per cent of those on board.

A major cleaning operation has now been launched targeting handrails, dining rooms and other public areas in a bid to protect the remaining 2,000 or so passengers and crew.

The 90,000-tonne ship, the second largest ever built by Cunard, is due to arrive at New York on Tuesday before travelling to the Caribbean for a two-week tour.

A spokesman for New York's City Economic Development Corporation, which is in charge of passenger arrivals, said it was monitoring the situation.

One passenger said: 'It's actually very worrying here at the moment. We've saved up a lot of money for this cruise and now we're scared to leave our cabins in case we come down with the illness.

'When the message came around that we might not be able to dock in New York our hearts sank as my wife and I have never been there and that was going to be the highlight of the trip.

'We're keen dancers, but we haven't even done that yet as that's the place where you're most likely to catch it.'

A spokesman for Cunard Line said: 'We can confirm that there have been a small number of reported cases of viral gastroenteritis among the passengers and crew on board Queen Victoria during her current transatlantic crossing to New York.

'The clinical symptoms are consistent with Norovirus, a mild but very common and highly contagious gastrointestinal virus, which is easily passed from person to person and this has been confirmed by sample analysis.'