Southwest Airlines said on Wednesday it has submitted a USD$7.5 million bid to buy bankrupt ATA Airlines in order to obtain its rights to operate at New York's LaGuardia Airport.

It's a significant move for the biggest US domestic carrier, which has only served the New York metropolitan market at the much smaller and more distant Islip MacArthur Airport on Long Island.

Southwest said its bid was submitted as part of the auction for ATA's assets in the US Bankruptcy Court in Indianapolis. Southwest said it had no plan to operate ATA or take on any of its planes, equipment or staff.

ATA, which entered bankruptcy in April, has 14 slots at LaGuardia, permitting up to seven daily round-trip flights from the airport.

Southwest would need approval from the bankruptcy court and Federal Aviation Administration and the Port Authority of New York and New Jersey before it could operate flights out of LaGuardia. It did not say what destinations such flights would serve.