A US court-appointed administrator has begun a two-week advertising campaign in UK national newspapers encouraging British Airways and Virgin Atlantic passengers to claim their share of a £73.5 million refund of fuel surcharges.

Advertisements appeared in six Sunday newspapers telling readers, “If you bought a BA or Virgin Atlantic ticket between August 11 2004 and March 23 2006 you may be entitled to a partial refund.”

BA and Virgin Atlantic are paying for the adverts and the £73.5 million refund in settlement of a class-action lawsuit brought in California after the pair admitted colluding on the level of fuel surcharges between the August 2004 and March 2006. BA was fined £121.5 million by the Office of Fair Trading and $300 million by the US Department of Justice last year following its admission of collusion. Virgin Atlantic escaped a fine after tipping off investigators.

About 100,000 individuals and 1,200 businesses have registered for the refunds so far. Only passengers who flew long-haul are entitled to claim, and refunds will vary from £4 to £20 per return ticket – based on one-third of the fuel surcharge on the fare.

The process depends on formal approval of the settlement by the US District Court for the Northern District of California expected on September 26. Passengers have until the end of December 2012 to apply.