Agents face paying a fee of up to £6.24 per sector on American Airlines’ bookings through Galileo and Worldspan from next month.

The carrier threatens to become the first to impose global distribution system (GDS) fees outside its home market as a result of an escalating row with GDS owner Travelport over access to content in the US. Until now, overseas airlines have feared GDS fees would cost them bookings.

Knock Travel managing director Doreen McKenzie, who chairs Abta’s aviation committee, warned: “It sets a precedent. But we shouldn’t just take it. My advice is ‘use someone else’.”

The fees will be £4.52 per sector on Worldspan and £6.24 on Galileo. Agents may escape them only by booking direct through the carrier’s Direct Connect facility.

Travelport confirmed it has “just over half the UK GDS market”, while the GTMC corporate travel association said more than half its members use Travelport.

Graham Bell, UK sales director, American Airlines wrote to agencies blaming the fee on “dramatic booking fee increases recently notified to American by Travelport”.

He wrote: “American will ask you to absorb the cost…known as the Booking Source Premium, to the degree necessary to bring the net cost in line with the cost of other GDSs.”

Bell’s letter followed a series of tit-for-tat moves in an escalating row over US online retailer Orbitz, in which Travelport has a controlling stake.

American announced it would end sales through Orbitz on December 1, and Travelport sued for breach of contract and withdrew negotiated discounts on its charges for the carrier’s GDS presence. A court hearing is due on December 3.

American will impose the fee on bookings from December 20.

Abta president John McEwan described the move as “alarming”, but said: “We hope there will be a compromise.”