The announcement is being seen as the most exhaustive attempt so far to discredit a US Congressional report earlier this year alleging China stole America's nuclear secrets.

At a news conference in Beijing on Thursday, government spokesman Zhao Qizheng angrily denounced the American allegations as "a slander on the Chinese people and our scientists."

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Beijing's decision to release the information comes at a sensitive time in the region and for relations with the US.

China is currently engaged in an escalating war of words with Taiwan over the island's efforts to gain formal recognition as a fully independent state.

US President Bill Clinton is also under pressure at home over his policy of engaging China through trade while not doing enough to protect US military secrets.

Parallel breakthroughs

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Mr Zhao said technological breakthroughs made by Chinese scientists had paralleled those of their US counterparts.

He added the charges of theft contained in a report by Republican Congressman Christopher Cox had obvious "racist" overtones.

"The Chinese can't be as smart as the Americans, therefore they must have stolen the technology," Mr Zhao said sarcastically.

A lengthy statement released by the official Chinese news agency Xinhua, gave details of Chinese nuclear research over the past 25 years.

It said Chinese scientists had also developed the ability to construct miniaturised nuclear warheads, as well as anti-submarine technology and "dispenser" techniques for launching multiple satellites from a single rocket.

'Logical' development

China insists its scientists developed bomb technology independently of the US

The statement said it was "logical" for China to develop a neutron bomb capability given the arms race then underway between the US and the Soviet Union.

"China had no other choice but to continue to carry out research and development of nuclear weapons technology and improve its nuclear weapons systems, mastering in succession the neutron bomb design technology and the nuclear weapon miniaturisation technology," Mr Zhao said.

Mr Zhao did not say when China developed the neutron bomb, or whether it had conducted tests or deployed the weapon.

China has repeatedly said its nuclear weapons programme is purely for defence purposes.

Lethal weapon

Neutron bombs kill people with extremely high levels of radiation able to penetrate armour or several metres of earth.

Unlike conventional nuclear weapons, the explosion and heat from a detonated neutron bomb is confined to a relatively small area.

China is thought to have detonated its first neutron bomb 11 years ago, but made no public announcement about the test.

BBC Beijing Correspondent James Miles says China is keen to demonstrate it is a world-class nuclear power capable of keeping up with the latest technology without resorting to espionage.

Systematic theft

The Cox report published in May this year alleged that China had systematically stolen detailed blueprints for virtually all the nuclear warheads in the US arsenal.

As a result, the report said, China's technological ability in the field of nuclear weapons had reached a par with the US.

Beijing has consistently denied the charges and dismissed the report's findings as sheer nonsense.

A 25,000 word rebuttal issued at the time said much of the information on the principle and structure of the neutron bomb alleged to have been stolen was in fact widely available on the Internet.

Anti-Chinese

Beijing says the report's authors were guided by an anti-Chinese bias.

However the Cox report sent shockwaves through Washington, with leading congressmen demanding that President Clinton do more to tighten security at US weapons research facilities

President Clinton has promised to do more to protect American nuclear secrets, while defending his policy of engagement with Beijing as being in the national interest.