American Airlines says preparations for an investment in Japan Airlines Corp. are at an advanced stage after Delta Air Lines Inc.

announced incentives to lure the Asian carrier into a new alliance. JAL would face a regulatory risk in leaving American's oneworld group and joining Delta's SkyTeam, Theo Panagiotoulias, director of Pacific operations for American, told reporters Thursday in Tokyo. Delta and AMR Corp.'s American, the world's two biggest airlines, are vying for access to JAL's routes in its home country and in China, Asia's largest air-travel market. Atlanta-based Delta unveiled its $1 billion proposal Wednesday, while American has not detailed its plan to keep JAL in oneworld. People familiar with the matter say American and private-equity firm TPG Inc. may offer as much as $1.47 billion to JAL, which is seeking a Japanese government rescue and new investors after losses in three of the last four years. JAL probably will stay in oneworld, Dow Jones reported, citing Shuta Saito, the airline's vice president. The Tokyo-based carrier will make a decision after agreeing on how to restructure itself with government aid, the report said. Charley Wilson, a spokesman for American, declined to comment in order to "respect the JAL restructuring process." American's oneworld partners are preparing their own proposals, which would be offered along with the plan from American and TPG, to help persuade JAL to stay. There is no schedule for making details public, oneworld managing director John McCulloch said.