Airbus has delayed the service-entry target for a hydrogen-powered aircraft developed under its ZEROe project by up to 10 years and axed plans to flight-test hydrogen propulsion systems, according to a French trade union.

Airbus SE said that one of its most ambitious projects for future propulsion — using hydrogen to power an aircraft — is progressing slower than planned because of the technological hurdles involved, dealing a setback to the industry’s efforts to clean up air travel.

Airbus acknowledged on Friday that progress on developing an aeroplane operating on hydrogen was slower than expected, but said it was not reviewing its approach to decarbonising aviation.