PHILADELPHIA, AUG. 13 -- A Pakistani pleaded not guilty today to charges that he and a retired Pakistani military official conspired to illegally buy and ship to their homeland two metals used in making nuclear weapons.

Authorities contend that Arshad Pervez, 43, of Ontario tried to bribe U.S. officials in order to buy and export the restricted metals to a Pakistani firm owned by retired Brig. Gen. Inam Ul-Haq.

U.S. Magistrate Edwin Naythons set a Sept. 21 trial date before U.S. District Court Judge James Giles. If convicted, Pervez could face 55 years in prison and fines of $1.75 million.

Undercover agents arrested Pervez in mid-July in Philadelphia when he allegedly tried to pick up a 25-ton shipment of the rare metallic chemical element beryllium and a superstrong steel called maraging 350, authorities said.

Export of the metals is regulated by the U.S. government because they are main ingredients of nuclear weapons and because Pakistan has refused to sign an international nuclear nonproliferation treaty.

Pervez and Inam were indicted on eight counts July 28, including charges of conspiracy to defraud the U.S. government and making false statements. Pervez also was charged with bribery, interstate travel in aid of racketeering and export violations.

Inam is believed hiding in Pakistan, U.S. authorities said.