Thousands of Chinese troops and paramilitary police fanned out across Tibet and neighbouring provinces as the Government acknowledged for the first time that pro-independence unrest in Lhasa had spilled into other far-flung corners.

The challenge facing those security forces was underscored by running protests that have been erupting daily for nearly a week in counties with large ethnic Tibetan populations. Schoolchildren have hurled rocks, students staged public vigils of mourning and nomads on horseback ripped down the Chinese flag.

Journalists who evaded police cordons to enter provinces surrounding Tibet proper described columns of military trucks, sometimes several miles long, winding up mountain roads towards the Himalayan plateau.

In the Tibetan capital, Lhasa — where Tibetan rioters vented their pent-up anger against Beijing last Friday by attacking ethnic Han Chinese and burning shops and offices — paramilitary and soldiers checked the papers of people on the street. Most were armed with iron batons but no violence was reported.

China’s response to last week’s violence — which it says was masterminded by the exiled Dalai Lama — has sparked international criticism and clouded preparations for the Beijing Olympics.

China finally revealed yesterday that the protests had spread to Sichuan and Gansu provinces. The acknowledgement of violence over an area about four times the size of France highlights the enmity now dividing many Tibetans and Han Chinese. A BBC journalist in western China counted convoys of more than 400 military vehicles heading for Tibet. With each lorry estimated to carry 30 soldiers that would mean the deployment of more than 12,000 extra troops into the already heavily militarised Himalayan region.

Officials said that calm was returning. But in Qinghai province, to the north of Tibet and the birthplace of the exiled Dalai Lama, residents said that paramilitary rushed to Jianzha county after pupils at the Tibetan Nationalities Middle School pulled down the Chinese flag and replaced it with the banned Tibetan snow lion standard. The children yelled “Long live the Dalai Lama”.

Students in a nearby county rushed into the streets a day earlier, hurling bricks and rocks at shop windows. About 40 military trucks were sent in.

Tibetans who work in Government offices are now required to vilify the Dalai Lama. China says 13 people were killed in the violence and three rioters died, while 325 were wounded. The Dalai Lama’s government-in-exile puts the toll as high as 99. Officials say that 24 people have been arrested formally and 156 have surrendered.

The Dalai Lama said that he was ready to talk to the Chinese President. “I [am] always ready to meet our Chinese leaders, particularly Hu Jintao.”

A documentary on state television to explain the violence interviewed a Han trader who sobbed as he described the death of his sister, 18, when a stairway collapsed in her burning shop. Another man wept as he recounted how angry Tibetans stamped on his six-year-old son and then attacked the ambulance taking him to hospital.

The programme emphasised the restraint exercised by Chinese security forces and accused the “Dalai Lama clique” of duping Tibetans. Little attempt was made to analyse the anger of Tibetans who yearn for the return of their leader and chafe at Chinese rule and its restrictions.

China has resisted calls for dialogue over the unrest and expressed concern that Gordon Brown plans to meet the Dalai Lama during a visit to Britain in May. “If those acts can be tolerated, is there any law in the world?” Chinese Foreign Ministry spokesman Qin Gang said.

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