The service from London to Singapore landed safely without any injuries to the 467 passengers and 27 crew on board, a Singapore Airlines spokesman said.

"Oxygen masks were deployed and the aircraft landed uneventfully at Baku airport at 01:03 (2103 GMT Sunday)," he told AFP by email.

In a statement posted on its Facebook site at 1100 GMT, the carrier said a replacement aircraft had left Singapore and was due to arrive in Baku at around 1900 GMT on Monday.

It is expected to land in Singapore on Tuesday afternoon.

"We sincerely apologise to affected customers for the inconvenience caused by the diversion and the lengthy delay encountered at the airport in Baku," the airline said.

Airbus said in a statement it was "following up on this issue and providing technical assistance to the airline".

Angry passengers took to social media to complain about being stranded in the Heydar Aliyev International Airport instead of being put up in hotels.

"We are not going to a hotel but will be flying out tonight after an 18-hour wait around the duty-free area," wrote passenger Nic Coulthard on the Singapore Airlines Facebook page at 0930 GMT.

"I don't think it is inconsistent for passengers to be grateful for a safe landing whilst disappointed at the lack of communication and facilities provided once on the ground," he wrote.

Another passenger, Terri Mann, complained that she had to sleep on a "cold steel bench" with her 17-month old child, and that there were no "food places" at the airport.

"We are all a little hesitant about getting on our next legs of our journeys, just hope the worst is over," she wrote.

Responding to a flood of posts on Facebook, Singapore Airlines noted that noise was reported from a door during an earlier flight of the same plane.

"The door was inspected by engineers on the ground in London with no findings, and the aircraft was cleared for continued operation," it said.

Passenger Matthew G. Johnson had said earlier that a "loud air noise was heard from the door five rows in front" shortly after take-off from Heathrow Airport in London.

Upon questioning, a crew member allegedly told him that the door had a "mild" leaking seal, Johnson said in a Facebook posting.

A few hours later oxygen masks were deployed and the aircraft began an emergency descent over Afghanistan after the cabin began losing pressure, he said.

His posting was accompanied by a photograph of a dimly lit cabin with oxygen masks hanging from the ceiling.

Singapore Airlines has a fleet of 19 Airbus A380s with five others on order, according to its website.

The planes are used for flights from Singapore to various destinations including Frankfurt, Hong Kong, London and Los Angeles.