Airbus signalled it would sue airlines refusing to honour contracts in the face of the coronavirus crisis.
The warning by Chief Executive Guillaume Faury in a news interview came as Airbus announced May deliveries well below normal, despite a partial recovery to 24 jets.
Planemakers and lessors have received multiple requests from airlines to delay deliveries due to the slump in air travel.
Faury told Politico that some airlines, which he did not identify, had refused to take calls at the height of the crisis, but that he hoped for a compromise.
Industry sources said such public warnings are rare in the tight-knit aviation market and could backfire.
But they noted the disruption is so great that Airbus is adopting a more aggressive stance, bracing itself for a repeat of turmoil such as the 2001 collapse of Swissair and Sabena.
It has sent out dozens of default notices to airlines in a step that can lead to lawsuits but undermine relations, the sources said. Some airlines have responded angrily in private.
Qatar Airways this week warned Airbus and Boeing to defer deliveries or face a loss of future business, without saying whether it had received any formal notices.
