It remains unclear whether a decision will be reached about closing down Germanwings, the sources said.

A Lufthansa spokesman said no decisions had been taken and reiterated that all options were being considered as it reviews its business and ways to cut costs to mitigate the loss of business caused by the coronavirus crisis.

German unions appealed on Monday for the airline's management to support Germanwings after Lufthansa last week rejected a union proposal to implement shortened work hours, also known as Kurzarbeit, which would have saved jobs in the short term.

Trade unions and associations VC, UFO, Verdi, IGL/TGL and ACA made a joint appeal on Monday to help safeguard Germanwings jobs.

Markus Wahl, president of Vereinigung Cockpit, said: "Great efforts will be necessary to overcome this crisis. We as trade unions in the Lufthansa Group offer our support for solutions that can be supported by all employees."

(Reporting by Alexander Ratz in Berlin, Edward Taylor and Ilona Wissenbach in Frankfurt; Editing by Sabine Wollrab and Peter Cooney)