Qantas’s plans for non-stop flights from Sydney, London and New York have suffered a setback, with Australian travellers now having to wait until 2027 for the ambitious plan.

Qantas' ambitious ultra-long-haul project will be postponed yet again because of delays with the specially modified Airbus A350-1000 aircraft.

The French manufacturer says the Sydney-to-London flagship will miss its 2026 deadline. Qantas investors say the $400m-a-year profit engine must be the top priority.