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 Defence University.

He then went on to say this could lead to the destruction of "hundreds" 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-defence 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.