A virus rather than food poisoning is looking like the most likely cause of mass illness suffered by passengers and crew aboard Thursday?s flight from London, British Airways said last night.

At least 30 passengers, most of them school children returning from English schools for half term, suffered vomiting, diarrhoea and headaches while sickness to crew grounded Saturday?s flight.

It left Sunday but the regular Sunday flight was grounded too and had to be combined with last night?s Monday flight after crew again were too sick to work.also had reports of passengers from Bermuda being sick after taking the outbound flight to London on Thursday although British Airways said no crew had reported sick from that flight.

Yesterday BA?s Bermuda spokeswoman Sallie Singleton said a thorough investigation was being carried out involving local staff, engineers and the BA health department in London.

The aircraft which operated on Thursday has been taken out of service and is being examined in London.

She said: ?The cause hasn?t been determined but it doesn?t seem from the tests they have done so far in London that there?s evidence of food poisoning.

?I don?t know what the Health Department has to say, it?s still too early to determine, but it looks more likely to be a virus.?

She apologised to customers for the delays and inconvenience.

Passengers who travelled on Thursday?s flight might be contacted by Health Department officials as part of its investigation into why many passengers and crew became sick.

Passengers who wish to report their symptoms to the Health Department are asked to call 239-3479 or 239-3542.

Chief Medical Officer Dr. John Cann said the department was pleased with the diligence of British Airways in taking preventative measures with its aircraft to prevent future outbreaks.

He was unable to shed any light on the cause of the outbreak.

?The Department of Health is exhausting all avenues to determine what caused this illness in order to prevent it from recurring,? Dr. Cann added.

Last night?s scheduled Monday flight was the last of the season which saw five weekly flights to London.

However British Airways will keep on four flights a week this winter ? one more than usual by keeping the Sunday flight.

BA?s Bermuda Manager Philip Troake said it would be the largest winter schedule since the airline launched a dedicated service in 1992.

He said: ?We are responding to the business community who have told us there is a demand for extra capacity.

?We are offering twice the number of seats we offered when we began dedicated service on this route 12 years ago, which is a tribute to our policy of nurturing steady yet careful growth.?

The winter service will operated on Tuesdays, Thursdays, Saturdays and Sundays.