Some leading U.S. lawmakers are accusing China of hampering an investigation into counterfeit electronics that ended up in U.S. weapons systems.

Senate Armed Services Committee Chairman Carl Levin and Senator John McCain spoke to reporters at a news conference in Washington Tuesday.

They said China has so far declined allow the committee's staff members to enter mainland China. Levin said Chinese officials informed the committee that even if visas were to be granted, a representative from the Chinese government would have to monitor the staff members' work.

Levin called that condition a “non-starter” .

The Chinese embassy in Washington did not immediately respond to VOA requests for comment on the matter.

The U.S. Government Accountability Office first identified the problem of counterfeit parts in a report last year. Levin says there are strong indications that the fake components originated in China's southern Guangdong province.

Senator McCain, who ran for U.S. president in 2008, warned Beijing it is in China's best interest to cooperate.

He said the problem of counterfeit parts would also hurt legitimate Chinese companies.

U.S. officials and lawmakers have said the use of Chinese components in defense systems could pose a security risk, in addition to hurting the U.S. economy.