General Zhu Chenghu's remarks made last month have been rejected as personal view by the Chinese government, which insists it would not be the first to unleash its nuclear firepower under any circumstances.

But US experts interpreted Zhu's comments as a tacit warning by Beijing to Washington of cataclysmic consequences if it confronted China over Taiwan.

"If the Americans draw their missiles and position-guided ammunition on to the target zone on China's territory, I think we will have to respond with nuclear weapons, warned Zhu, dean of China's National Defense University.

He then went on to say this could lead to the destruction of "hundreds" of of American cities.

Chinese Foreign Minister Li Zhaoxing Li insisted the general was speaking in a personal capacity, saying Beijing would not be the first to use nuclear weapons "at any time and under any condition."

But considering China's nuclear might, there is a possibility of it launching an atomic strike even before coming under attack, said Eric McVadon, an ex-defense attache at the American embassy in Beijing.

"It is not a simple straight forward question as to whether under all circumstances, China would never under any situation use nuclear weapons first," he told AFP.

"So, we probably shouldn't completely ignore General Zhu's words and remember in that context," said McVadon, a part-time director of Asia-Pacific studies at the US Institute for Foreign Policy Analysis.

Zhu's comments came five months after China adopted a law allowing it to use force against any secession moves by Taiwan, triggering concerns in Washington, which is bound by law to offer the island the means of self-defence if its security were threatened.

"There is little doubt that Chinas military leadership wants the US to believe that it will use nuclear weapons against the US should it rise to defend democratic Taiwan from Chinese attack," said Richard Fisher of the International Assessment and Strategy Center, a Washington-based think tank.

Zhu is the grandson of late Chinese leader Mao Tsu-tung's long time chief of staff, an important pedigree in the People's Liberation Army, Fisher said, describing China's nuclear deployments as having "coercive" potential.

The PLA, he said, now deployed a new fixed and a new mobile nuclear intercontinental ballistic missile system, he said.

In addition, China would soon deploy a longer-range mobile intercontinental ballistic missile, and about the same time, deploy a new long-range submarine-launched ballistic missile.

These new nuclear missiles -- three of which may contain multiple warheads -- would be active within five years, he said.

China is also on its way to acquiring 50 to 60 nuclear and conventional attack submarines, Fisher said.

At present, Chinese nuclear-tipped missiles are capable of reaching the US mainland without being intercepted. Zhu's remarks could draw greater support for a US missile defense system.

The size and pace of China's weapons acquisitions, estimated at 90 billion dollars this year, could threaten the military balance with Taiwan, a Pentagon report warned recently.

China considers Taiwan a part of its territory that must be brought back under its rule even though the island has been ruled as a de facto independent state since the end of the Chinese civil war in 1949.

The United States, on the other hand, is the leading arms supplier to Taiwan.

Chas Freeman, a former senior Pentagon official who helped reopen defense dialogue with Beijing, said Zhu had made "a serious point which needs to be taken seriously by planners on both sides.

"I don't think it was a threat of any kind or represents policy. I think it represented an analytical point," he said.

"What it shows is that there has not been enough thinking on both sides about the implications of an escalation in a Taiwan crisis," Freeman said.