Building the bomb: North Korean exiles reveal 15 year history of nuclear cheating

North Korea had developed a nuclear bomb by the end of the 1980s and probably has many such weapons after pursuing its secret programme under the noses of international inspectors, according to defectors from the country.

The defectors have revealed in interviews with The Independent the extent to which the impoverished communist state cheated on its international agreements as it diverted scarce resources into the clandestine programme. They also confirm that Pakistan provided crucial help for North Korea, which yesterday described a confession by Pakistan's top nuclear scientist that he had sold nuclear technology to North Korea as "nothing but mean and groundless propaganda".

Details began to emerge in October 2002, when the United States forced North Korean officials to admit it had been running a uranium-enriching programme to build a bomb. Kim Dae Ho, who worked on the nuclear programme for 10 years until defecting in 1994, said: "I saw classified documents in 1987 in which (the then North Korean leader) Kim Il Sung said we have finally developed a highly enriched uranium programme in a self-reliant way.

"Then in 1989 he announced that we finally have the centrifuge technology and are making weapons-grade uranium. He ordered the state to reward scientists with the best available gifts including Toshiba colour TVs."

Mr Kim was smuggled out of China on a Chinese fishing vessel in great secrecy. Until recently he has been forced to keep a low profile, but is now publishing a book.

Another eyewitness, a North Korean nuclear technician who left the country two years ago after working and living for years in North Korea's nuclear-research centre in Yongbyon, confirmed that the country had acquired nuclear weapons by enriching uranium and by extracting plutonium by spent fuel rods from the 5-MegaWatt (MW) experimental reactor at Yongbyon. He said: "By the end of the 1980s we had the bomb. They began hiding the research facilities in tunnels." He refused to go into details for fear of endangering relatives still in the country.

Mr Kim said North Korea extracted 26.4lbs of plutonium from fuel rods during shutdowns of the reactor in 1989, 1990 and 1991 - enough to build three nuclear warheads.

In 1994 Washington and Pyongyang signed a landmark deal under which North Korea agreed to freeze its nuclear-weapons programme in exchange for free oil deliveries and the gift of two light-water reactors worth $4.5bn (£2.4bn). But Mr Kim said: "The work intensified after 1994. It never stopped."

The two technicians are part of a growing stream of North Koreans escaping to the South and providing evidence which undermines the position of the current South Korean government, which wants to present Kim Jong Il, the North Korean leader, as a reliable partner, and former members of the Clinton administration, who defend the 1994 deal and are horrified by the tough line taken by the current US government.

The Bush administration is believed to have drawn on the testimony of such escapees to gather evidence that North Korea had never intended to stick to any of its promises nor treaties made to Seoul, Washington or the International Atomic Energy Authority (IAEA). The CIA had accumulated enough evidence of the uranium-enriching programme for James Kelly, the US Assistant Secretary of State, to take to Pyongyang in the autumn of 2002. North Korea first admitted the allegations were true butlater retracted the confession. The 1994 Agreed Framework collapsed and Pyongyang expelled the IAEA inspectors.

North Korea had relied on Soviet help until the 1970s to develop a nuclear industry, but the programme was accelerated in 1984 when Kim Jong Il took control of the government after his father, Kim Il Sung, slipped into semi-retirement.

"Kim Jong Il assigned two army regiments to exploit North Korea's natural deposits of uranium in Pyongyang province and set up a special fund called N710 to finance their work. They were given the very best of everything," Mr Kim said.

More than 30,000 soldiers were assigned to the programme which had three key sites: an underground uranium mine, a subterranean nuclear-test centre, and the 5-MW Yongbyon nuclear reactor near Mount Yaksan.

In the early 1990s, IAEA inspectors focused efforts on monitoring the 5-MW Yongbyon reactor and trying to determine if North Korea had diverted spent fuel rods to extract plutonium.

"We spent months hiding the nuclear processing plant from the IAEA inspectors. The most difficult thing was preventing the release of tell-tale krypton into the atmosphere," Mr Kim said.

Other defectors said North Korea became convinced from the 1991 Gulf war that the US might launch a pre-emptive strike against its nuclear facilities after Saddam Hussein was found to be much closer to building a bomb than suspected. North Korea did everything it could to fortify or hide its facilities.

Although North Korea's leadership claimed that the achievements were the fruits of its self-reliant Juche philosophy, Mr Kim said the uranium-enrichment programme benefited from Chinese know-how and materials. After the collapse of the Soviet Union, Pyongyang also recruited large numbers of unemployed former Soviet and East German weapons experts.

Although Mr Kim said he knew little about Pakistan's help, North Korea might not have succeeded without it. In the early 1980s the two countries made a deal under which North Korea delivered medium-range missiles to Pakistan so it could threaten India. In return, Pakistan provided North Korea with the blueprints stolen by Abdul Qadeer Khan, the father of Pakistan's nuclear programme, when he worked in Europe in the 1970s.