In a heated argument that threatens to delay the restart of European shipments to the Gulf carrier, Qatar Airways has clashed with the European plane manufacturer AirBus to paint an A350 jetliner, according to industry sources.

Chief Executive Akbar Al Baker criticized Airbus for the lack of details, but the sources said the latest in a series of airline-Airbus quality-control spats.

Qatar Airways and Airbus refused to comment on the matter.

“We talk to our customers constantly. We maintain confidentiality about the content of these discussions, “A representative of Airbus said that.

Qatar Airways boasts exceptional scrutiny to detail in line with a premium brand, but aerospace executives have accused it of seizing on such details in the past to delay taking delivery of jets it no longer needs, a suggestion it has often denied.

The clash over paint quality comes at a sensitive time as Airbus tries to enforce delivery of dozens of jets built for airlines that either can’t or won’t take delivery amid a slump in demand because of the coronavirus pandemic.

Airbus has sent out dozens of “default notices” or legal warnings to airlines over undelivered jets since the crisis began.

Chef Executive Guillaume Faury has threatened legal action against airlines that refuse to take deliveries.

Qatar Airways’ Al Baker was quoted by Bloomberg earlier on Monday as saying the airline would refuse to take new aircraft from Airbus if it was not able to resolve the dispute.

Last year Al Baker said the airline would not take deliveries of any aircraft in 2020 or 2021 due to the coronavirus crisis. He later said the airline had reached an agreement with Airbus over delays. Details were not disclosed.