Delays to a Qantas flight out of Melbourne left more than 300 passengers stranded at the city's airport overnight.

The airline says the Hong-Kong-bound flight was supposed to leave at 11:00PM, but damage to a panel on the plane's wing meant it couldn't take off.

Qantas says the 308 passengers weren't offered accommodation because staff thought the problem would be fixed quickly.

The flight left shortly after 6:00AM.

Earlier this week, the Civil Aviation Safety Authority (CASA) told Qantas to improve the maintenance of its planes, after a mid-air emergency and a series of cancellations and delays.

An audit by CASA has found the airline's maintenance procedures are not up to its own standards.

But Mick Quinn from CASA says the deficiencies are not linked to the airline's recent safety incidents.

"Qantas is a safe airline and CASA has no doubt about that, if it wasn't a safe airline, we'd be taking a lot more stringent action under our regulations to put it on the ground." he said.

Federal Transport Minister Anthony Albanese says CASA will now carry out two further audits of some Qantas planes and their service records, as well as the airline's overall maintenance procedures.