British Airways has been carrying out research for months on whether to introduce random breath tests for its pilots and cabin crew.

The move was prompted by the introduction of random tests in other parts of the transport industry, including railways.

BA insisted the research was well under way before it suspended 11 pilots and three cabin crew from duty following allegations that they drank alcohol before flying aircraft into Gatwick.

An internal investigation was continuing today into allegations by Channel 4's Dispatches programme that pilots drank excessive amounts of booze.

No UK airline carries out random testing but it happens in the United States.

Pilots' contracts would have to be renegotiated if random tests were introduced in this country.

A BA spokeswoman said: "We have been carrying out research in the UK and abroad for months, following the introduction of random testing in other transport industries."