A spokesman told a news conference in Beijing that police had seized guns, bullets and explosives in some Tibetan Buddhist monasteries and repeated the accusation that the Dalai Lama was linked to Tibetan groups that had organised the recent unrest.

An aide to the Dalai Lama immediately denied what he called "baseless" allegations, and the U.S. State Department said the Dalai Lama was a man of peace who wanted only to talk to China.

At the same time, China's anti-riot force was issued a mobilisation order to ensure a trouble-free Beijing Olympic Games in the wake of the anti-Chinese unrest across Tibetan areas.

The Dalai Lama's representatives in India, where he has lived in exile since 1959, have denied Beijing's charges of his complicity in deadly riots that swept Tibet's regional capital on March 14 and urged Beijing to allow an international probe.

But China's Ministry of Public Security said it had arrested "key members" of an underground network in Lhasa working in concert with overseas pro-Tibet independence groups to spark a "Tibet People's Uprising Movement".

"We now have sufficient evidence to prove that the Lhasa incident is part of the Tibetan People's Uprising Movement organised by the Dalai clique. Its purpose is to create crisis in China by staging coordinated sabotage activities," ministry spokesman Wu Heping told the news conference.

"To our knowledge, the next plan of the Tibet independence forces is to organise suicide squads to launch violent attacks."

Wu linked the recent unrest with gatherings of Tibetan rights groups last year and in January, saying that the Tibetan Youth Congress and other participants set down a blueprint to disrupt the Olympics and stir insurrection in Tibetan areas.

"They reached agreement after consulting with high-level leaders in the Dalai clique," Wu said.

Pressed to give the names of arrested suspects, or to say whether China wants to extradite and try the exiled Dalai Lama -- winner of a Nobel Peace Prize -- for the alleged crimes, spokesman Wu backed off into generalities about "rule of law".

He also would not give details of the supposed plans for suicide attacks, instead referring to his claims of weapons seizures in monasteries.

The United States rejected the allegations that the Dalai Lama was involved in plotting any kind of violence.

"The Dalai Lama is a man of peace. There is absolutely no indication that he wants to do anything other than have a dialogue with China to discuss how to deal with some of the serious issues there," said State Department spokesman Tom Casey, when asked about China's claims.

He reiterated a U.S. call for China to engage in a dialogue with the Dalai Lama. "We continue to urge the Chinese government to exercise restraint in terms of dealing with any protests that are out there," Casey added.

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Wu said that investigators had seized 176 guns, 13,013 bullets and 3,504 kilograms of explosives, but did not say where. "The Dalai Lama was in fact an energising force in guiding this movement," he said.

Tenzin Taklha, a senior aide of the Dalai Lama, said China should stop making baseless allegations, take a realistic look at the grievances of the Tibetan people and engage in dialogue with the Dalai Lama.

"Again, the Chinese are trying to portray that we Tibetans are instigating violence and now they are talking about suicide squads and we strongly deny these allegations," he said.

Some foreign leaders, including U.S. President George W. Bush, have urged China to talk to the Dalai Lama to resolve the crisis, but China has been pressing foreign governments to avoid contact with him.

The Dalai Lama will make a brief stopover in Japan en route to the United States from India next week, upsetting China.

"We have all along opposed him using any excuse or in any capacity going to any country to engage in separatist activities," Chinese Foreign Ministry spokeswoman Jiang Yu said.

In India, where the Dalai Lama and many of his followers have lived since 1959 when they fled China, Foreign Minister Pranab Mukherjee urged the Dalai Lama not to indulge in political activities that hurt its ties with China.