The government is likely to scrap plans for the domestic development of a successor to the Air Self-Defense Force's F-2 fighter jet due to expected huge costs, government sources said Saturday.

The government is expected to consider international joint development as the main course of action, the sources said.

The F-2 fighter was jointly developed by Japan and the United States at a cost of ¥327.4 billion. The development started in 1988.

Since the first F-2 was deployed in 2000, about 90 jets are now in operation.

With the fleet of F-2 fighters set to retire around 2030, the government is considering a successor plane.

Eyeing domestic development in line with a request from the defense industry, the Defense Ministry has spent ¥138 billion in research costs since 2009, including for producing the X-2 experimental stealth jet.

But as substantial costs are additionally expected for domestic development, many in the ministry now believe such plans are "unrealistic," one official said.

The ministry has already contacted U.S. and British companies for information, planning to assess potential improvements to existing fighters.

The ministry has three options for the successor jet - joint development with other countries, upgrade to an existing fighter model or purchasing U.S. fighters.

The government is hoping to pick one from the three within this year, in preparation for the planned review in late 2018 of the national defense program guidelines, the sources said.