Japan's Board of Audit has found that no Japanese-made parts were used in state-of-the-art F-35 fighter jets, violating a contract with the United States.

Japan's Defense Ministry plans to introduce 42 of the stealth aircraft as the next-generation mainstay fighter of the country's Air Self-Defense Force.

The jet was jointly developed by the US and 8 other countries. Its production started in 2012.

Japanese subcontractors were supposed to join the production the following year, with a view to nurturing the country's defense-related industry.

But Board of Audit officials found that 2 aircraft ordered in 2013 have no Japanese-made parts.

This is attributed to a delay in delivery from the US of materials for the parts.

The officials suggest that domestically-produced parts may also not be used in 4 F-35s now in production.

Source: ANNnewsCH