As a direct result, the CIA trebled the number of its agents spying on aspiring nuclear states, primarily North Korea and its hardline president, Kim Il-sung.

North Korea is by far the most dangerous of a growing pack of countries that have either successfully developed a bomb, have nuclear weapons programmes or are technically capable of manufacturing atomic devices. It is still unclear if North Korea has developed a weapon or is playing a dangerous game of bluff with the International Atomic Energy Agency (IAEA), the US and South Korea.

Equilibrium was kept delicately balanced between the traditional nuclear powers - France, Britain, the US, China and the Soviet Union - for more than 40 years, following the end of World War II, by the Cold War.

It was an uneasy atomic standoff in which the protagonists maintained a lasting, if not always stable peace - unsettled by incidents such as the Cuban missile crisis and the shooting down of Korean Air Lines flight 007 - based on a principle that no onewanted to be first to use weapons of mass destruction.

But with the breakup of the Soviet Union, communism on the retreat around the globe and Asia becoming an economic powerhouse and consequently spending billions on dollars on self-defence, the balance of power is shifting.

More significantly, IAEA control over the countries that have nuclear weapons and access to facilities of ''threshold countries'', which could develop nuclear arsenals, is becoming increasingly difficult to monitor.

And when China set off a nuclear test last year at its restricted Lop Nor facility in a remote part of Xinjiang province, it resulted in a backlash of criticism from around the world.

It also acted as a reminder to non-nuclear Asian states that Beijing has been a nuclear power for about 30 years and is developing further weapons which could be used in future conflicts.

Patricia Lewis, director of the London-based Verification Technology Information Centre said she believed China was testing a warhead for a new submarine-launched missile. If this is the case, then countries such as Taiwan, Vietnam, Malaysia and the Philippines - which, along with Beijing, dispute the sovereignty of the Paracel and Spratly islands - could feel obliged to boost their own defences as a precaution.

Western experts are concerned the test could act as a catalyst for other countries in the region to speed up their own development or to institute otherwise dormant weapons programmes. China has now carried out 39 nuclear tests, compared with 44 by Britain, 192 by France, more than 930 by the Soviets and more than 1,000 by the US, which - until last December - concealed the existence of 250 tests since the late 1940s.

But fears that the mainland will use reprocessed nuclear waste from the newly-opened Daya Bay plant, which is only 50 kilometres from Central, for its secretive weapons programme are seen as unlikely. A nuclear industrial source in Hong Kong said it washighly improbable that Beijing would use the spent fuel to make warheads.

''It would be economically stupid,'' the scientist said. ''China already has the ability to produce nuclear weapons without reprocessing waste. They use natural uranium, with an enriched quality, and plutonium, processed from reactors designed just for weapons-grade plutonium.'' The scientist said China already had secret installations housing reactors producing plutonium, which cannot be found naturally and produces more destructive warheads than uranium-based weapons.

He said if Beijing went ahead with this procedure, only three per cent of the waste would be nuclear-grade material after reprocessing and, of that, only a tiny amount would be plutonium, which could be used in the weapons programme.

HOWEVER, North Korea, which has been at the centre of a year-long dispute, is proceeding with its weapons programme while negotiations to allow IAEA inspectors into the country to check its sensitive underground Yongbyon plant go from one impasse to another. Pyongyang blocked planned inspections last year and said it would withdraw from the Nuclear Non-Proliferation Treaty, which is due for renewal next year. It suspended the withdrawal decision last June but still has not agreed to on-site inspections required by the IAEA.

The Stalinist state is widely thought to have enough plutonium to make at least one atomic bomb, although it could lack the technology to assemble detonators and other essential parts. In a sign of the increasing tension on the peninsula, South Korean President Kim Young-sam has ordered his cabinet to take every precaution to safeguard national security amid mounting concerns over the North's nuclear weapons development.

''In case dialogue and efforts fail, the government must take all necessary measures to safeguard national security and survival and to win public confidence,'' Mr Kim said.

South Korean national security adviser, Chung Jong-uk, said intelligence reports showed the North had been conducting defence training around its main nuclear complex at Yongbyon. Mr Chung said Pyongyang had fortified the underground military facility, 98 km north of Pyongyang, but there was ''no clear indication that North Korea'' was ''trying to provoke outright military provocations''. These moves come less than two weeks before the IAEA votes on whether to refer North Korea's continued refusal to allow nuclear inspections to the UN Security Council for possible international sanctions.

On a global scale, IAEA officials know that Israel, Pakistan and India have all developed bombs clandestinely, while Iran is actively involved in producing an atomic weapon with the help of China, which also assisted Pakistan.

Iraq, which had an advanced programme before the Gulf War, is now out of the running due to ongoing inspections and controls by the United Nations.

And countries such as Japan, South Korea and Taiwan are technically capable of starting weapons programmes, although it would take some years for them to be in a position to begin production.

On the other extreme, South Africa, which admitted to having manufactured six bombs, has now dismantled the weapons and destroyed the documentation in an apparent bid to prevent them falling into the hands of a government run by the African National Congress.

Other countries, such as Libya, Algeria, Egypt, Brazil and Argentina have dropped out of the race for a number of reasons. Three former members of the Soviet Union - Belarus, Ukraine and Kazakhstan - which became independent nuclear states on the breakup of the Soviet Union, have declared they do not want atomic weapons - although a practical procedure for removing hundreds of nuclear warheads from the countries has yet to be agreed.

Last week, Kazakhstan President Nursultan Nazarbayev denied Iranian reports that the central Asian country was rethinking its commitment to eliminate the nuclear weapons it inherited from the Soviet Union. The nation will ''fulfil its obligations beforethe international community'' and send all of its 104 SS-18 nuclear missiles to Russia for dismantling, Mr Nazarbayev said.

The 53-year-old Kazakh leader is scheduled to go to Washington this week to see President Bill Clinton. The summit was arranged after Kazakhstan's parliament ratified the Nuclear Non-Proliferation Treaty in December, reaffirming its intention to become a non-nuclear state.

On another positive note, Bulgaria, which supplied uranium for the Soviet Union's first atomic bomb, announced it planned to phase out production of uranium concentrate. But the move could cause further headaches for the IAEA, as Sofia also planned to sell off a 500-tonne stockpile of the material on the international market. The agency stated its concern last month at the legal vacuums in nuclear controls in the disintegrated Soviet Union and the opportunities that could open up for ''uncontrolled elements'' obtaining nuclear material.