In the latest incident on 14 May, up to 80 Tibetans were injured, including many monks and nuns, according to reports from Lhasa. A week earlier three monks were shot and injured during a disturbance at the Ganden monastery, 25 miles east of the capital, and at least 40 were arrested.
The details, obtained by the London-based Tibet Information Network (TIN), are the latest evidence of increased tensions as Peking tries to tighten its hold on the region.
The edict against the display of photographs in monasteries and temples of Tibet's exiled spiritual leader was published on 5 April. Hotels and restaurants were also told to remove the Dalai Lama's picture.
A month later on 7 May, a government work group was sent to Ganden monastery to implement the new regulation. The monks protested. Fighting broke out between the groups, and police were called in. TIN said at least three of the 500 monks at Ganden were shot and wounded, and a fourth is in a serious condition after police struck his head.
The two main monasteries in Lhasa, Drepung and Ramoche, were sealed off by the Chinese authorities to stop the unrest spreading. The main temple in Tibet, the Johkang, in central Lhasa, staged a one-day shutdown in protest, said TIN.
Details of the latest incident, on 14 May appear to confirm another confrontation over the picture-banning. This information was provided by a Japanese tourist who was looking after his sick American girlfriend at the Lhasa People's Hospital Number One.
At 11.30 that night two truckloads of wounded monks and nuns were brought to the emergency unit, and about 30 women and 15 men were off loaded under police escort for treatment.
"They took the people out of one truck ... more than half of them young nuns. Some people were walking, some people could not walk. They were holding each other and some were crying and screaming," said Takeo Fujimoto, who contacted TIN after he reached Nepal.
"I am 100 per cent sure that somebody beat them up. It was not like a car accident. Their whole faces were sore and covered with blood, and some people could not move."
The second truck was driven off. "On the other truck I saw some legs hanging out from the back of the truck. They did not move," Mr Fujimoto said.
Those taken in at the hospital were mostly monks or nuns, but there were also lay Tibetans. "One was a young girl who had been beaten in the face," Mr Fujimoto said. TIN suggested the confrontation took place at a pilgrimage site.
The latest edict categorises pictures of the Dalai Lama as "reactionary propaganda".Reuse content