The airlines are among five Oneworld partners who have applied for immunity to anti-trust cases, which would let them jointly price and market international flights without fear of prosecution. Similar deals already operate for the Star and SkyTeam groupings.
However, the US Justice Department ruled last night the proposals “would result in competitive harm on certain trans-Atlantic routes serving 2.5m passengers annually”, predicting prices could rise by up to 15 per cent.
As well as giving up takeoff and landing slots, the agency said the carriers should give up six routes.
BA responded angrily. “We will be making a robust response to the US Justice Department’s comments,” a spokesperson said.
Virgin Atlantic, which is not a member of Oneworld and which has led the campaign against the proposals, said: “We continue to urge to regulators to reject the proposals.”