Two air stewardesses were prevented from boarding a British Airways flight from Helsinki to London, after allegedly failing a breath test.
The incident delayed the flight by almost three hours
BA confirmed two cabin crew members were taken to the airport police station in the Finnish capital on Saturday.
Seats were found on other flights for most of BA's 112 passengers, after the incident seriously delayed the 0740 (0540 BST) flight to London.
The crew had spent Friday night in Helsinki, a spokesman said.
BA is waiting to hear from police in Finland, before deciding what action will be taken, said a spokesman.
He said breath tests are given where officials can "show cause" to justify it.
He could not confirm who had carried out the test, but said that at London's Heathrow Airport, it was within the powers of the police.
Flight BA795 arrived in London carrying 31 of its original passengers at 1306 BST, almost three hours late, he added.
A deal with Finn Air meant BA was able to get most of its passengers onto alternative flights, said the airline.
Pilots, cabin crew and air traffic controllers are subject to a limit of 20mg of alcohol in 100ml of blood.
In March this year the government gave police powers to test suspected offenders, with penalties as high as a £5,000 fine or two years in prison.
BA's rules state crews should only consume alcohol in moderation in the 24 hours before reporting for duty.
They should not consume any alcohol in the last eight hours and should have no residual alcohol in their bloodstream when reporting for duty.
BA captain Graeme Holden, from the Isle of Man, lost a claim for unfair dismissal in September 2003, after BA dismissed him over a breach of its alcohol rules.
Two other pilots, arrested after allegedly being over the company's alcohol limit, resigned in November that year.
Captain William McAulliffe, 50, and first officer David Ryan, 26, had been held at Oslo airport shortly before going on duty for a scheduled flight to the UK.
In February 2003 pilot Simon Robinson of Wrecclesham, Surrey, was sacked for "gross misconduct", after being breathalysed before a flight from Sweden to London Heathrow.