Disgraced Pakistani scientist AQ Khan supplied North Korea with centrifuges and their designs, President Pervez Musharraf has confirmed.
AQ Khan has been under house arrest since his confession
Centrifuges enrich uranium which can be used for making nuclear bombs.
It is the first time Pakistan has given details about the type of technology Dr Khan transferred to Pyongyang.
But President Musharraf told Japanese news agency Kyodo that Dr Khan had not provided North Korea with the expertise for constructing a nuclear bomb.
Dr Khan has admitted leaking nuclear secrets to North Korea, Libya and Iran. Pakistan's government has always denied any involvement.
"Yes, he passed centrifuges - parts and complete. I do not exactly remember the number," President Musharraf told Kyodo.
The centrifuges are essential components for enriching uranium, which can be used as fuel for civilian nuclear power reactors or making atomic weapons.
But President Musharraf said Dr Khan was not involved in the conversion of uranium into gas or other key steps needed to make the bomb.
"He does not know about making the bomb, he does not know about the trigger mechanism, he does not know about the delivery system," Gen Musharraf said.
"So if North Korea has made a bomb... Dr AQ Khan's part is only enriching the uranium to weapons grade."
Regarding the additional technology, the president said North Korea "must have got it themselves or somewhere else - not from Pakistan".
The president's spokesman, Maj Gen Shaukat Sultan, confirmed Gen Musharraf's remarks while downplaying Dr Khan's role in helping North Korea acquire a nuclear bomb.
"Saying that someone made a bomb because Khan passed on a couple of centrifuges to them, maybe a dozen of them, this does not mean they can make a bomb," he told Agence France Presse.
Until now, Pakistan has revealed few details about the transfers that Dr Khan made, particularly to North Korea, although it says it has briefed the UN's nuclear watchdog.
The international community is locked in a stand-off with Pyongyang after it announced in February 2005 that it had built nuclear weapons for self-defence.
Six-party talks aimed at persuading the nation to abandon its nuclear activities, involving the US, Russia, China, Japan and South Korea, are set to resume next week.
Dr Khan has been under house arrest since his public confession in February 2004 that he illegally transferred nuclear technology to countries including North Korea, Libya and Iran.
The man still regarded by many Pakistanis as a national hero was given a pardon by President Musharraf because of his services to the nation's nuclear industry.
Dr Khan has not been allowed to receive visitors and international investigators probing global nuclear proliferation have not been allowed to question him.
Pakistan this year confirmed Dr Khan had supplied nuclear centrifuges to Iran.
President Musharraf has previously said the discovery of the Khan network was the most embarrassing episode in his political career.