Seoul: North Korea possesses some 4,000 tonnes of biochemical weapons and has built as many as three crude nuclear weapons, South Korea's intelligence agency chief told lawmakers.

In testimony to the Parliament's Intelligence Committee on October 28, Shin Kun, director of the National Intelligence Service, said the North was capable of producing some 4,500 tonnes of weapons annually.

Pyongyang began its biochemical weapons programme about four decades ago. "The North is believed to have a stockpile of between 2,500-4,000 tonnes of biochemical weapons," an Opposition Grand National Party (GNP) lawmaker, Lee Yoon-Sung, quoted Shin as saying.

"We are unable to judge how powerful those biochemical weapons are as we have yet to confirm the accuracy of their delivery systems and whether the North has made those weapons compact enough to deliver."

Echoing what US officials have said of the North's nuclear development programme, Shin said Pyongyang could already own as many as three crude nuclear weapons.

The weapons would have been built using some seven to 22 kilogrammes (15 to 49 pounds) of plutonium the North is believed to have extracted before it opened nuclear facilities to International Atomic Energy Agency inspections in 1992.

"We don't have any information on how much enriched Uranium the North might have. South Korea and the United States have been closely following this programme," he said.

A disclosure by Washington that Pyongyang admitted it was secretly developing nuclear weapons and considered the 1994 Agreed Framework "nullified" alarmed South Korea and Asian neighbours, and prompted the United States to demand an "immediate and verifiable" scrapping of the programme.

But Pyongyang, which denied that US envoy James Kelly had presented evidence of such a programme during an October 3-5 visit, said the envoy's trip showed the Bush administration wanted to stifle it by force and put brakes on rapproachment on the Korean peninsula.

North Korea charged that Washington itself had violated the deal, under which Pyongyang had pledged to freeze its atomic ambitions, by threatening it with nuclear weapons and listing the country as part of an "axis of evil" with Iraq and Iraq.

Pyongyang last week offered to resolve US concerns over nuclear weapons in return for a non-aggression pact, but rejected Washington's bottom line that it end its nuclear weapons development before talks could begin.

In a defiant bid to head off the US-led pressure to scrap its nuclear weapons program, North Korea urged South Korea on October 29 to join forces against the United States by backing the communist state's "army-centered" policy.

"It is a vital task of all Koreans in the North and the South and abroad to uphold the great Army-centred policy under the present grave political situation where the sovereignty of the country and the cause of national reunification are seriously jeopardised by the vicious challenge of the US," the North's Committee for the Peaceful Reunification of the Fatherland said in a statement carried by official media.