Terrorist groups have obtained neither nuclear weapons nor know-how from Pakistan, an official said on Monday.
"We exclude the possibility," military spokesman Major-General Shaukat Sultan said, when asked if Dr Abdul Qadeer Khan's leaked nuclear technology and hardware could have reached groups like al Qaeda.
"It has not come out of our investigations, or any other intelligence agency. There has been no such hint."
The government insists there have been no nuclear leaks from Pakistan since the National Command Authority (NCA) was established in February 2000 to oversee the arsenal.
But a Pakistani military C-130 transport plane was in North Korea in 2002, leading to suspicions in the West of a swap of Pakistani nuclear know-how for Pyongyang's missiles.
Sultan told Reuters that the plane was in North Korea to buy SA-16 shoulder-held surface-to-air missiles to reinforce its arsenal during the stand-off with neighbouring India when the South Asian rivals came to the brink of a fourth war.
"Pakistan was already making this missile...and they are called Anza in Pakistan. We felt we needed more. The C-130 went and picked up the missiles and the payment was made according to proper transactions; it was in hard cash." Sultan said the acquisition was forced on Pakistan due to India's air superiority, and called for international pressure to prevent a widening arms imbalance between the nuclear rivals.
India is likely to sign a $1.1 billion deal with Israel within the next month for three early warning radar systems. India has also expressed interest in the Arrow anti-ballistic missile system, but the United States has not approved the sale.
"These are new elements being introduced in the India and Pakistan scenario. They are going to result in an arms race and tilt the balance back in India's favour," Sultan said.
An investigation launched in November has thrown light on a nuclear black market involving middlemen in countries including Sri Lanka, Malaysia, Germany and the Netherlands.
Dr Qadeer, part of the network, is accused of helping Iran, North Korea and Libya acquire atomic weapons technology and equipment.
The United States, worried about "rogue" states obtaining nuclear arms, says it fears al Qaeda-type groups might gain access to weapons of mass destruction to use against Americans.
Quoting sources close to al Qaeda, a pan-Arab newspaper said on Sunday Osama bin Laden's shadowy network bought tactical nuclear weapons from Ukraine in 1998 and is storing them.
Ukrainian officials denied the report on Monday, saying the country never controlled the former Soviet arms on its territory which had passed straight into Russian hands.