China warned on Saturday it would use a firm hand to quash the biggest protests in Tibet for decades, acknowledging 10 people had been killed in unrest there just months before the Olympic Games.
Witnesses said tanks were in the streets of the Tibetan capital Lhasa as part of a heavy security clampdown after violent riots erupted on Friday following days of protests against China's controversial rule in the region.
China's top official in Tibet, a vast region formally annexed by the country in 1951, said the protests were part of a "separatist" movement that authorities would not allow to succeed.
"The plot of the separatists will fail. We will challenge them firmly, according to law," the chairman of the Tibet government, Qiangba Puncog, told reporters in Beijing on the sidelines of China's annual parliamentary session.
"This is very clear: This is a separatist Dalai Lama clique, inside and outside the country."
The Dalai Lama, Tibet's spiritual leader, called on China to "stop using force" and rejected allegations that he and his government-in-exile in neighbouring India were behind the uprising in Lhasa.
"These protests are a manifestation of the deep-rooted resentment of the Tibetan people," he said. "Unity and stability under brute force is at best a temporary solution."
China's official Xinhua news agency reported that Lhasa was calm on Saturday morning but acknowledged there had been "windows smashed, shops robbed, and a mosque burnt down."
It said that 10 people were killed in the rioting, most of them business people and none of them foreigners.
Earlier Xinhua said many police officers had been badly injured in clashes and that rioters had wielded "backpacks filled with stones and bottles of inflammable liquids, some holding iron bars, wooden sticks and long knives."
An official in the city's medical emergency centre said several people were killed in Friday's unrest and that many others were injured. Radio Free Asia reported at least two people had been killed by Chinese bullets.
A Chinese resident of Lhasa, speaking to AFP by phone who declined to let his name be used, said there were tanks and armoured personnel carriers in the streets on Saturday morning.
"There are many armed police, special police and People's Liberation Army soldiers everywhere," he said. Three tour operators told AFP that foreign tourists had been blocked from coming into Lhasa.
Tibet, a mountainous region that straddles Mount Everest and is more than twice the size of France, has been a flashpoint issue for China's Communist leadership ever since it came to power in 1949.
Communist forces were sent into Tibet in 1950 to "liberate" the region, with its official rule beginning a year later.
Tibet has taken on greater importance in the run-up to the Olympics in August, which the country's leaders hope will be a chance to show off China's rapid transformation into a modern economic power to the rest of the world.
Tibetan rights groups have vowed to pile intense pressure on China over its rule of the region ahead of the Games, and any perceived rights abuses now would prove unwelcome news for the Chinese leadership.
Chinese censors blacked out Western media reports about the developments in Tibet on Chinese television on Friday, and independent verification of the news from the region has been difficult to verify.
But even official Chinese accounts have indicated the protests began Monday, when Tibetans around the world marked the anniversary of a 1959 uprising that was put down with force and led the Dalai Lama to flee into exile.
Those protests, reportedly begun by Buddhist monks, grew in the following days before erupting into anti-Chinese rioting on Friday.
Chinese-owned shops, offices and restaurants were smashed and burned by demonstrators.
The unrest spread outside Lhasa, with monks leading a rally of up to 4,000 people in Xiahe, Gansu province, the site of one of Tibetan Buddhism's most important monasteries, said the Free Tibet Campaign, an activist group.
The United States and Britain expressed concern over the violence, with the White House calling on Beijing to "respect Tibetan culture."
China has come under repeated international criticism over its human rights record and its treatment of minorities, not only in Tibet but also in the western Muslim region of Xinjiang.
Rights groups allege that Beijing encourages ethnic Chinese to move into Tibet to culturally take over the region, a process made much easier by the government opening a new rail line to Tibet in 2006.