SINGAPORE, Sept 10, 2007 (AFP) - An online auction for seats on the first commercial flight of the super jumbo Airbus A380 was set to close Monday night, with every available seat expected to sell, Singapore Airlines said.

The two-week auction on the eBay marketplace was to end late Monday night or early Tuesday, Stephen Forshaw, the airline's vice-president of public affairs, told AFP.

Singapore Airlines (SIA) is to be the first commercial airline to fly the double-decker A380, the world's biggest passenger plane, when it begins service to Sydney on October 25.

Seats on the return leg to Singapore the following day have also been up for bids.

"Bidding activity on all of them by the time it closes will have been very, very high," said Forshaw.

While the auction essentially ends on Monday night, "odd lots" of about five seats in each direction, mostly in business class, have been held back and will likely remain on the block for three to five more days, he said.

"That'll be last-chance," Forshaw said.

He said response to the online sale has exceeded the airline's expectations, but he declined to say how many seats will have been sold, or to provide further details, until Tuesday after the auction ends.

A majority of seats on the plane were up for bids, SIA said earlier.

Proceeds from the auction are to be divided equally between a Singapore charity, two childrens' hospitals in Sydney and the international relief agency Medecins Sans Frontieres.

SIA has committed to buy 19 A380s despite a series of delays that pushed back delivery from early last year.