"North Korea is believed to have extracted up to 50 kilograms (110 pounds) of plutonium," the defence ministry was quoted by Yonhap news agency as saying in the report.

The North has extracted plutonium from spent fuel rods in nuclear reactors at its Yongbyon site.

The report was submitted to a meeting of top military commanders on October 10, a day after North Korea conducted its first nuclear test which sparked international condemnation and United Nations sanctions.

A defence ministry spokesman said he was checking the existence of such a report.

Defence ministry authorities also told the October 10 meeting that nuclear bombs could be carried by North Korea's Ilyushin 28 jet bombers, according to Yonhap.

North Korea deploys a total of 82 of the Soviet-designed aircraft at Uiju, 125 kilometers (78 miles) northwest of Pyongyang and at Jangjin, 130 kilometers northeast of the capital, the ministry said.

The aim of the North's nuclear test was to compensate for its failure in test-firing a long-range missile in July and to press the United States to enter into negotiations, the ministry said.

According to Yonhap, Seoul defence officials fear the test could spark a nuclear arms race in Northeast Asia, disturb the balance of power on the Korean pensinsula and intensify international sanctions against the North.

Defence Minister Yoon Kwang-Ung said on October 13 that North Korea wa believed to be developing nuclear warheads for its missiles but needs "a few more years" before it can produce them.

earlier related report
China confirms weapons arrests but stays mum on uranium
Beijing (AFP) Oct 26 - China said Thursday that two people had been arrested for trafficking "dangerous weapons" but stopped short of confirming a South Korean media report that uranium was involved.

The pair were arrested on October 16 in Beijing on charges of "alleged trading in illegal dangerous weapons", foreign ministry spokesman Liu Jianchao said during a press briefing.

Liu would not specify the nature of the materials being traded or the nationalities of those involved.

He was responding to a question about a report in South Korea's Chosun Ilbo newspaper on Tuesday that Chinese police had arrested a pair of ethnic Koreans for trying to sell about 970 grams (34 ounces) of enriched uranium.

It quoted a Beijing police source as saying the enriched uranium "was presumed to be Russian-made", but it could also have come from North Korea.

Large numbers of ethnic Koreans in China engage in illegal cross-border trade with hermetic North Korea.

The report did not say how enriched the uranium was. Fifteen to 17 kilograms of highly enriched uranium would be needed to produce a nuclear weapon, it said.

Defying international pressure to scrap its nuclear program, North Korea tested a nuclear weapon on October 9, triggering UN sanctions aimed at crippling the program.

The sanctions also mandated inspections of North Korean cargo, as the test raised concerns about whether Pyongyang may intend to smuggle its nuclear material and technology out of the country and into the hands of terrorists.

earlier related report
SKorea to ban NKoreans suspected of links to nuclear programme
SEOUL (AFP) Oct 26 - South Korea said Thursday it would ban the entry of North Koreans suspected of links to nuclear and other weapons programmes -- its first move to enforce UN sanctions imposed after the North's nuclear test.

The Unification Ministry brushed off a threat of retaliation if the South joins in imposing sanctions, saying in a statement it would faithfully fulfil its duties as a UN member.

Lee Jong-Seok, head of the ministry which is responsible for inter-Korean relations, separately told parliament an existing law authorises controls over visits by all North Koreans and their stay here.

When the UN sanctions committee names those North Koreans subject to travel restrictions, the government would be able to control or prevent their entry under the same law, he said.

Lee said his government is also tightening inspections of goods and materials shipped to the North, under the Security Council resolution.

In addition to weapons-related material the resolution bans the transfer of luxury goods -- an apparent attempt to crimp the luxurious lifestyle of the North's leader Kim Jong-Il.

Lee said no luxury goods were being allowed into the North from his country, and missile and other weapons-related items have long been subject to strict monitoring.

"There are no North Korean assets in the South that are related to WMD (weapons of mass destruction) programs," he told a parliamentary committee.

"Once the sanctions committee designates persons or organizations (with links to North Korea's WMD programs), the government will control the country's trade, investment, financial payments and fund remittances" to those entities, Lee said.

South Korea, which has long practised a "sunshine" policy of engagement with its impoverished communist neighbour, has pledged to enforce the sanctions but has taken a softer line than Japan and the United States.

A state-controlled body in Pyongyang, the Committee for the Peaceful Reunification of the Fatherland, warned Seoul Wednesday against trying to punish it for the October 9 test which sparked worldwide shock.

"If the South Korean authorities, bereft of reason, dare join in the US moves to put sanctions upon the DPRK (North Korea) and stifle it, we will take appropriate steps, regarding it as a total negation of the June 15 joint declaration and a declaration of confrontation with fellow countrymen," it said.

The South will pay "a dear price" if it joins the international efforts, the committee said.

The June 15 declaration was issued at the end of a historic inter-Korean summit in 2000 in Pyongyang.

The unification ministry dismissed the threat as unreasonable.

"To support and implement the UN Security Council resolution is what the government must do as a UN member and one in charge of peace on the Korean peninsula, and the government will faithfully fulfil its role," it said in a statement.

It called the nuclear test "a serious threat" to regional peace and urged the North immediately to return to stalled six-party talks on dismantling its nuclear program.

Minister Lee Wednesday announced his resignation, effective next month, amid growing criticism of the way the 'sunshine" policy works.

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