American Airlines may team with private-equity firm TPG Inc. to invest at least $300 million in alliance partner Japan Airlines Corp., a source familiar with the plan said.

That sum would be competitive with a proposed investment in JAL by Delta Air Lines Inc., said the source, who declined to be identified because the talks aren't public. Delta, a member of the SkyTeam group of airlines, wants to lure money-losing JAL from American's oneworld group.

TPG would bring experience in working with troubled carriers, including helping return bankrupt Continental Airlines Inc. to profit in the early 1990s. JAL is due to receive bridge loans from the Development Bank of Japan while a government-affiliated fund considers providing financial assistance.