By Paul Lewis
BBC Radio 4's Money Box
People who flew long haul between 2004 and 2006 may be in line for compensation after two airlines have admitted colluding over prices.
British Airways and Virgin Atlantic were fierce competitors
British Airways and Virgin Atlantic discussed when to impose fuel surcharges on long haul flights.
Such deals are illegal under competition laws and lawyers say passengers could recover the charges.
The airlines are resisting any claim and say the charges would have been imposed anyway.
That argument was dismissed by Michael Hausfeld of lawyers Cohen, Milstein, Hausfeld, and Toll who are taking a class action on behalf of customers in the USA.
He told Money Box on BBC Radio 4: "There could have been a surcharge.
"But competitive conditions up to that point were preventing either company from imposing a surcharge.
"If the timing [had been] different that would have meant some large portion of passengers would not have been surcharged, while others were.
"And if there was that lag between carriers, the first carrier who moved may have had to rescind."
And he said his firm would help UK customers recover the surcharge too.
"We intend to bring a companion litigation if necessary in the UK, so that UK residents are not discriminated against."
Deborah Prince, head of legal affairs at the UK consumer organisation Which?, also told the programme that passengers may be able to get compensation.
"The BA-Virgin case is looking promising as there has been and admission of anti-competitive activity.
"Technically [passengers] do have the right to bring a claim as long as they can show they suffered loss as a result of unlawful activity."
She said that Which? may take its own action and passengers could join in.
"We can bring what is called a follow-on case and say - we've got the claimants, now we want compensation.
"It is a tool we are using and of general good for consumers."
The surcharges were between £5 and £60 during the period.
Passengers who believe they have a claim will have to wait until next year before Which? or the US lawyers take the matter on.
Meanwhile they should keep receipts or credit card statements as proof of their flight.
Both airlines have apologised to passengers but say they have no claim.
BA told the BBC "The fuel surcharge... never fully recovered the actual cost of the fuel... therefore we do not believe passengers were overcharged."
And Virgin Atlantic said "We do not believe it resulted in loss to customers.
"The total ticket prices charged to our passengers were not higher as we continued to compete fiercely."
BBC Radio 4's Money Box was broadcast on Saturday, 8 September 2007 at 1204 GMT.