North Korea said Thursday it has reprocessed 8,000 nuclear fuel rods and plutonium extracted from them could be used to strengthen its "nuclear deterrent force." At the same time, a senior North Korean official is reportedly saying that his government will not export its nuclear capability.

A statement from the North Korean foreign ministry carried by the official Korean Central News Agency says that North Korea is manufacturing nuclear bombs with the material siphoned off from reprocessing 8,000 spent nuclear fuel rods.

The comments are raising tensions over North Korea's nuclear weapons programs and worsening a year-old dispute over the isolated nation's nuclear ambitions.

The statement from North Korea also says that the country's nuclear activities are only for peaceful purposes, which parallels comments from Vice Foreign Minister Choe Su Hon, who says that Pyongyang does not intend to transfer its nuclear know-how to other countries.

Mr. Choe's comments, which were carried by China's official Xinhua news agency, were delivered to reporters at North Korea's mission to the United Nations in New York. He reportedly says that North Korea's nuclear weapons are for self-defense only.

But the United States and its allies in Asia worry that North Korea could test or sell a nuclear weapon. The United States has long said that Pyongyang probably has one or two nuclear weapons, but some U.S. intelligence experts say the Stalinist state may possess up to six.

North Korea's latest claims come days after it warned it was taking "practical measures" to increase its nuclear deterrent against attacks by the United States. It frequently accuses the United States of plotting an attack, a claim Washington has denied over and over again.

As tensions escalate, diplomatic maneuvers continue. Japan is a close neighbor and potential target of North Korean hostilities. On Wednesday, Japanese Foreign Minister Yoriko Kawaguchi told parliament that Japan is working closely with other countries to end the North's nuclear program.

She says Japan, the United States and South Korea plan to ask North Korea to dismantle its nuclear programs and that North Korea has repeated a request for a security guarantee from the United States.

She also says that Japan would be willing to discuss economic aid to the North after it abandons its nuclear weapons.

Japan, the two Koreas, the United States, Russia and China held one round of talks in Beijing in August to try to resolve the nuclear standoff, but the discussion ended without resolution, except for a general agreement to hold more talks.

So far, a second meeting has not been scheduled. Pyongyang has at times implied that further talks would be useless but has told its close ally Beijing that it would take part in such a meeting.