The carrier said the relief plane carrying nearly 500 passengers and crew was expected to land back in Singapore at around 0745 GMT after taking off from the capital Baku.

"A replacement aircraft that was sent from Singapore to collect affected customers has now departed Baku," it said in a statement on its Facebook site. A spokesman confirmed the relief plane was also an A380 superjumbo.

"Customers with onward missed connections will be rebooked on other flights," the airline said.

The original flight from London to Singapore was forced to make an emergency landing at the Heydar Aliyev International Airport in Baku Monday due to a loss of cabin pressure.

No one was injured but oxygen masks were deployed on the A380.

Singapore Airlines was forced to apologise to passengers for a lengthy wait before they were transferred to hotels, as many took to social media to complain they were stranded at the airport with few amenities.

"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," passenger Nic Coulthard wrote on the airline's Facebook page.

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.

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.