Thousands of soldiers were seen in Lhasa on Thursday amid reports of a huge military build-up, as the Dalai Lama expressed fears China's crackdown on Tibetan protesters had caused many casualties.
Long military convoys were on the move in Tibet while a build-up of troops also took place in nearby provinces, after a week of violent unrest against China's rule of the region, witnesses, activist groups and media reports said.
"We saw a big convoy of military vehicles with troops in the back," German journalist Georg Blume said, giving a picture of Lhasa, Tibet's capital, on Thursday morning.
"One convoy was about two kilometres (1.2 miles) long and contained about 200 trucks. Each had 30 soldiers on board so that's about 6,000 military personnel in one convoy."
Blume, from German newspaper Die Zeit, and another witness in Lhasa said they had seen security forces going from one house to the next.
"There are lots of security forces on the streets. We can see Chinese security going door-to-door. It's very tense," an independent source in the city, who did want to be named for fear of retaliation, told AFP by phone.
A week of protests against China's 57-year rule of Tibet erupted into rioting in Lhasa last Friday. Demonstrations have since spilled over into nearby Chinese provinces with ethnic Tibetan populations.
China said rioters killed 13 innocent civilians in Lhasa while denying that it used deadly force to end the protests. Exiled Tibetan leaders have said about 100 people were believed to have been killed in the Chinese crackdown.
The Dalai Lama, Tibet's spiritual leader who fled his homeland after a failed uprising against Chinese rule in 1959, on Thursday expressed concerns for the many people he said had fallen victim to the Chinese security forces.
"We don't know exact numbers. Some say six, some say 100, but places have been cut off. There are movements of Chinese troops. I am really worried a lot of casualties have happened," he said from his base of exile in India.
The unrest has been a public relations nightmare for China in the leadup to the Beijing Olympics in August, an event the nation's communist rulers had hoped would showcase a harmonious country.
While no government has called for a boycott of the Games, China has faced increasing international pressure to resolve the unrest peacefully and to hold talks with the Dalai Lama.
The 1989 Nobel Peace Prize winner said Thursday he was prepared to meet Chinese President Hu Jintao.
But China all but ruled out talks, with foreign ministry spokesman Qin Gang referring to the Dalai Lama as a double-dealing "splittist" bent on Tibetan independence.
The Dalai Lama has repeatedly said that he does not want independence for his homeland, but instead seeks greater cultural autonomy under Chinese rule and an end to what he describes as widespread repression.
British Prime Minister Gordon Brown said on Wednesday he planned to meet with the Dalai Lama, triggering a swift response from Beijing.
"We have expressed our great concern over that," Qin, the foreign ministry spokesman, told reporters.
Australia added to the pressure on Thursday, with Foreign Minister Stephen Smith expressing concern over the violence and calling on China to allow foreign journalists and diplomats access to Tibet and other hotspot areas.
China has banned foreign journalists from Lhasa and tried to block them from the nearby western provinces of China, where a spate of violent protests have taken place over the past week.
Germany's Blume was ordered out of Lhasa on Thursday, and there are now believed to be no more foreign reporters in the capital.
Nevertheless, reports of the huge troop build-up in Lhasa and the nearby provinces emerged.
More than 400 vehicles were seen heading to Tibet through mountain passes in western China, a BBC reporter said, without specifying his location because of Chinese restrictions on foreign press reporting in the area.
"Over the past two days I've seen increasing numbers of troops heading for the Tibetan border but this is the largest deployment by far," the reporter said.
Large troop movements also took place in southwest China's Sichuan province, bordering on the Tibetan Autonomous Region and home to several large Tibetan populations, one foreign reporter there told AFP.
Authorities have arrested 24 people linked to the protests in Lhasa, while 170 people have surrendered to police, state-run Xinhua news agency reported.
Activist groups say hundreds of Tibetans have been arrested. (AFP)
China pours troops into Tibet