The Japanese government has issued warnings to Sumitomo Heavy Industries Ltd. and a subcontracted firm after the latter leaked blueprints for parts of a military-use prototype machine gun to a Chinese company, the company and the government spokesman said Thursday.

The Ministry of Economy, Trade and Industry issued the warnings on April 28 on the grounds that the subcontractor had violated Japan's foreign exchange and trade control law, as the weapons were to be procured for Japan's Ground Self-Defense Force if selected in a tender.

Sumitomo Heavy had bid to procure the machine guns in the tender opened by the GSDF in fiscal 2019 but withdrew its participation in March as the number of machine guns to be produced was small and the project lacked business prospects.

In order to manufacture prototypes of the weapon ahead of its adoption, some component blueprints given to the subcontractor were provided to a Chinese firm without authorization.

The subcontractor has told Sumitomo Heavy it was not aware the parts were for weapons.

Sumitomo Heavy pledged to enforce thorough oversight of its subcontractors moving forward.

"It is regrettable that such a case has occurred, and we will endeavor to deal with it appropriately," Chief Cabinet Secretary Katsunobu Kato, the government's top spokesman, said at a press conference on Thursday.