"We would consider taking a stake in American Airlines if that is something that American would welcome," an IAG spokeswoman said on Sunday.

Her comments followed a story in the Mail on Sunday, which cited IAG Chief Executive Willie Walsh as saying that IAG would be open to buying a stake if there was a strong strategic argument for investment, adding that any investment would be small.

A source close to IAG (ICAG.L) said the possibility of buying a stake in American (AAMRQ.PK) was not linked to any bid by Delta.

But American is seen as a target for Delta, and if such a takeover were successful, that would break up the oneworld alliance and strengthen competition against IAG on transatlantic routes.

"American Airlines is key to IAG's oneworld alliance. and IAG will do anything they can to prevent the likes of Delta or US Airways (LCC.N) from grabbing it," said an aviation sector banker who declined to be named.

"They could for instance offer to buy a 25 percent shareholding in American, the maximum allowed under U.S. law." (Reporting by Rhys Jones and Rosalba O'Brien, editing by Jane Baird)

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