Authorities have raided British Airways as part of a trans-atlantic investigation into an alleged cartel over airfares and fuel surcharges which saw BA suspend two senior executives.

American Airlines, United Airlines and Richard Branson's Virgin Atlantic said they were also involved in the probe, which is being conducted jointly with US authorities, but were not direct targets.

Those four airlines are the only carriers allowed to fly direct between Heathrow Airport and the United States under bilateral treaties.

BA, Europe's third-largest carrier, said the investigation by Britain's Office of Fair Trading (OFT) and the US Department of Justice related to passenger ticket prices, including fuel surcharges.

All parties declined to comment on whether the investigation was limited to trans-atlantic airfares or had a wider remit.

The carrier said its Commercial Director Martin George and Head of Communications Iain Burns had been given leave of absence during the investigation.

"We would be very surprised if a specific issue relating to BA's pricing has developed. Unfortunately, though, putting key personnel on leave is a difficult signal for the market to interpret," Deutsche Bank analysts said in a note.

Analysts said the maximum BA could be fined if found guilty was 10 percent of turnover on the routes involved. UBS said this would amount to a maximum GBP