After Qatar Airways has grounded nearly half of its A350 fleet and has taken the dispute with Airbus to the High Court in London, the European planemaker announced that it has “terminated” a contract with one of the Gulf region’s “big three” carriers for 50 single-aisle A321neo aircraft.

In an escalating feud over the grounding of A350 aircraft, Qatar Airways has stopped accepting further deliveries of the wide-body aircraft from Airbus until the problem with degradation of exterior fuselage surfaces is resolved.

The aerospace giant has acknowledged the existence of paint degradation, which can expose a metallic mesh that protects aircraft from lightning strikes.

But Airbus says the issue poses no air safety problems.

Qatar Airways demanded $618 million in compensation, plus $4 million more per day for each day the A350 planes have been kept idle.

In return, Airbus has taken an astonishing step of canceling Qatar Airways’ multi-billion-dollar order of 50 aircraft, “in accordance with its rights.”

According to the plane maker, it cancelled the A321neo orders because Qatar Airways failed its contractual obligations by refusing to take deliveries of A350 planes.

The order was worth more than $6 billion at catalogue prices, though airlines are usually charged less for large purchases.

The two companies had their first hearing in London High Court on Thursday.

A new hearing is scheduled for the week of April 26.