Pakistan is denying reports that the U.N. nuclear agency has asked it to submit sample centrifuges as part of an investigation into Pakistan's illicit nuclear sales to Iran.

Foreign Ministry spokesman Jalil Abbas Jilani says Pakistan is cooperating with the U.N.'s International Atomic Energy Agency to prevent proliferation of nuclear weapons.

He told reporters here the nature of that cooperation is necessarily confidential. But he said there is no truth in the reports that Pakistan will send used centrifuge parts to the IAEA to help identify the source of enriched-uranium traces on equipment in Iran's controversial nuclear program.

"Pakistan has not been asked to give centrifuges nor will Pakistan do so," said Jalil Abbas Jilani. "In cooperation with the international agency, let me say categorically that we will be strictly guided by our national interests and also the imperatives of protecting our strategic assets."

Iran has long maintained its nuclear program is for civilian use, a claim that has been called into question by the discovery of highly enriched uranium. Tehran maintains the uranium came from contaminated equipment it purchased from the nuclear black market and not its own enrichment activities.

Pakistan's Information Minister Sheikh Rasheed Ahmed admitted last week that the founder of the country's nuclear-weapons program, Abdul Qadeer Khan, provided Iran centrifuges without the knowledge of the government.

Foreign Ministry Spokesman Jilani says that information has already been shared with the IAEA.

"We have been saying all along that there were some clandestine transfers, which took place at some stage," he said. "Those transfers were investigated by us and we shared the results of those investigations with the international agency and our efforts were greatly appreciated by IAEA."

Secretary of State Condoleezza Rice is arriving in Pakistan later this week to hold discussions with Pakistani leaders on a wide range of issues, including nuclear proliferation.