A technical fault with a type of wing flap on a Qantas jumbo left 341 passengers stranded in Hong Kong airport for almost 15 hours overnight after the airline was unable to find accommodation for them.

"There was some sort of conference in town and all the hotels were fully booked," a Qantas spokeswoman said this morning.

"Our ground staff tried a number of options, including dividing up the group of passengers to try to get them into a range of hotels but there was no accommodation available," she said. "They tried everything."

The plane, a Boeing 747, had flown the QF30 route from London to Hong Kong on Wednesday evening, and had touched down in Hong Kong at 5:20 p.m. yesterday.

A fault was found with an aileron -- a type of flap -- on one of the aircraft's wings, during pre-flight checks in the 90-minute turnaround period in preparation for its leg to Melbourne.

The Qantas spokeswoman was unable to say whether the problem was electrical, hydraulic or mechanical, but it could not be immediately fixed.

Qantas issued blankets and food vouchers to passengers, as they settled in for an enforced break on hard airport floors or bench seats.

Travellers with children were granted Qantas lounge access, turning it into an impromptu child-minding centre.

As morning dawned today, Qantas had put another plane into service, bumping 243 passengers from the outbound QF29 Hong Kong-London flight.

They had to be found flights with alternative airline that are partners with Qantas in the Oneworld alliance.

The Melbourne-bound passengers left Hong Kong this morning after 8 a.m. local time.