Pakistan has denied an Iranian opposition claim that Iran received a nuclear bomb design and enriched uranium used in such weapons from a leading Pakistani scientist. Iranian authorities also have denied the allegations.

Pakistan Foreign Ministry spokesman Masood Khan says the allegation is baseless, but his country is ready to help with any investigation.

"We don't attach importance to this report or claim," he said. "The validity of this claim is being questioned and it is being viewed with skepticism."

A senior member of an exiled Iranian opposition group told reporters in Vienna Wednesday that the founder of Pakistan's nuclear weapons program, Abdul Qadeer Khan, had transferred a design for a nuclear bomb to Iran in the mid-1990s, and then sent highly enriched uranium in 2001.

Pakistan has admitted that Mr. Khan was involved in illegal transfers of nuclear secrets to countries such as North Korea, Libya and Iran. But Pakistani officials say they have investigated the scandal and shared their findings with the International Atomic Energy Agency, or IAEA.

Foreign Ministry spokesman Masood Khan says Pakistan is still cooperating with the agency but it has not received any report or communication from the IAEA or Tehran on the Iranian opposition group's allegation

"Our investigations are not closed, they are still open, they are continuing," he said, "but we haven't received any communication which would provide a solid lead and suggest that such [a] transaction had taken place."

Despite the expression of cooperation, Pakistan has refused to allow the IAEA to question Qadeer Khan directly.

The Pakistani scientist made a televised apology for his role in the nuclear proliferation scandal in February. The government pardoned him, citing his services to the national security.

He is closely guarded at his home in the Pakistani capital, although authorities insist that he is not under house arrest.