The Defense Agency decided Monday to delay the planned completion of its F-2 next-generation support fighter by about nine months, due to various shortcomings found in the prototype aircraft, Vice Defense Minister Masahiro Akiyama said.

Jointly developed by Japan and the U.S. as a modified F-16 multirole fighter, the F-2 fighter is expected to come as a replacement for the F-1 air-superiority fighters of the Air Self-Defense Force.

The Defense Agency had planned to complete the F-2's development by the end of fiscal 1998, in March 1999, but delayed this until December 1999 after admitting that it had "discovered various shortcomings and is forced to make a nine-month delay in completing trials and improving the strength of the fighter's body," Akiyama told a news conference Monday.

In describing the flaws found in the F-2 prototypes, another agency official pointed to a lack of strength in the wings and rear body against the acceleration of gravity. The official added that the agency has already fixed a possible "flutter" of the fighter's wings by the rearrangement of its armament-stores' stations.