A Muslim nuclear physicist on Thursday accused the US Department of Energy of revoking his security clearance in retaliation for his criticism of the government's treatment of Muslims. Moniem El-Ganayni, 57, an Egyptian who moved to the United States in 1980, had worked at the Bettis Laboratory in suburban Pittsburgh for 18 years. He was fired in May after the department revoked his security clearance, according to a federal lawsuit filed by the American Civil Liberties Union on his behalf. The ACLU is an organization that advocates individual rights. The Department of Energy denied El-Ganayni the right to appeal the revocation by saying its reasons are classified and could violate national security if made public. El-Ganayni is demanding that he be allowed to contest it before a "nonpolitical, neutral arbiter" as mandated by department regulations. "Everything I strived for all my life came to an end without a chance to defend myself," El-Ganayni said.