Airbus has cancelled a $6bn contract with Qatar Airways for 50 of its new A321neo passenger jets, escalating a legal battle between the two companies overpainton the recently delivered A350s.

Qatar Airways called Airbus’s decision announced on Friday “a matter of considerable regret and frustration”.

In December, Airbus was taken to court by Qatar Airways in London, following a series of alleged problems withthe Airbus A350 aircraft.

The airline complained the paint on the recently delivered Airbus A350s was cracking and peeling, exposing copper meshing used to insulate the aircraft against lightning strike.

It is seeking more than$600min compensation after grounding the affected aircraft – 21of its 53 A350 jets – claiming the paint issue is a safety risk.

The deal wasreportedly worth $6.35bnwhen it was finalised in December 2017.

Qatar Airways published a videoon social media on Friday of the scarred exterior ofgroundedA350 jets that the airline said underscored “serious and legitimate safety concerns”.

The European Union Aviation Safety Agency independently assessed the issue and found no safety concerns.

“There is no reasonable or rational basis” for Qatari regulators to have grounded the A350s operated by Qatar Airways, Airbus said in documents prepared for a London court hearing on Thursday.

It accused Qatar Airways of instigating the grounding as it was in its own financial interest to keep the aircraft on the ground in light of thecoronavirus pandemic collapsein demand for air travel.

Qatar Airways rejected the claims in a statement on Friday.

“These defects are not superficial and one of the defectscauses the aircraft’s lightning protection system to be exposed anddamaged,” it said.“We continue to urge Airbus to undertake a satisfactory rootcause analysis into the cause of the defects.”

An investigationby Reuters news agency showed at least five other airlines reported A350 paint or skin flaws since 2016, well before Qatar raised concerns in November 2020 when an attempt to repaint a jet in World Cup livery exposed some 980 defects.

Airbus has said it is looking at changing the design of anti-lightning mesh for future A350s, but insisted there is adequate backup lightning protection. It says Qatar is undermining global protocols by seeking leverage over safety. (Text, excludes headline courtesy Al Jazeera)