Claiming that China holds a substantial nuclear threat that is being underestimated by the US leadership, a Chinese pro-democracy leader has warned that a Sino-US nuclear war over Taiwan could not be ruled out in the near future.

"In the past, China may have felt it was not time for them to confront the US," Wei Jingsheng, who spent about 18 years in Chinese prisons before his release in 1997, was quoted as saying by a media report.

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"Now things are different. Now the Chinese feel that they need to use these kinds of nuclear threats. China is very serious about that. The nuclear threat from China is not theoretical," he said.

Wei, in an interview to The Washington Times, claimed that he has heard from government officials in China, including some within the military, who are worried by the growing chance of a nuclear war.

He said President George W Bush [Images] and other US leaders do not fully understand the chances of a conflict breaking out and must do more to avert it.

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Wei claimed that social unrest in China was rising and its leadership was divided by factions headed by President Hu Jintao and former President Jiang Zemin. There were also elements within the military who think that a war to retake Taiwan should begin as soon as possible.

"There are many conflicts within the military," he said.

To avert war, Wei urged the Bush Administration to put more pressure on China's government in the areas of human rights and trade.