GENEVA, Aug. 8 (Xinhua) -- The two Swiss engineers, Urs and Marco Tinner, suspected of involvement in an international nuclears muggling network were refused bail on Friday, the official Swissinfo news website reported.

    The Swiss Federal Court upheld a ruling by the Criminal Court earlier this year which ordered the Tinners to remain in custody pending the outcome of an investigation, according to the report.

    The pair, who have been detained since 2005, had argued their alleged involvement could no longer be proven after the government ordered the destruction of documents on the case.

    The brothers along with their father, Friedrich Tinner, are suspected of helping to supply parts for Libya's nuclear weapons program through a trafficking ring run by Abdul Qadeer Khan, the founder of Pakistan's nuclear program.

    It is believed the three worked as undercover agents for the United States intelligence service amid speculation that the Swiss government was asked by Washington to destroy any evidence suggesting cooperation with the CIA.