Dalai Lama's northern India-based government-in-exile said it had confirmed 99 deaths in the government's crackdown.
The Dalai Lama said on Thursday that he feared "a lot of casualties" from China's crackdown on protests in Tibet.
"We don't know exact numbers. Some say six, some say 100, but places have been cut off," he said.
"There are movements of Chinese troops. I am really worried a lot of casualties have happened."
Protests were reported in Gansu and Qinghai, provinces adjoining Tibet.
In one protest in Gansu, thousands of ethnic Tibetans tried to storm a government building.
They were filmed tearing down a Chinese flag and replacing it with a Tibetan one.
Xie Yanjun, the Lhasa deputy chief prosecutor, said "they should be severely punished to protect the strictness of the law".
Chinese authorities say 325 people have been injured and 16 people killed so far - including three protesters who allegedly jumped from windows while trying to escape police.
|More Chinese forces were deployed in Tibet |
and neighbouring areas on Wednesday [AFP]
Xinhua, China's state news agency, said the protesters attacked "shops and government offices" on Sunday in Aba, known as Ngawa in Tibetan.
It said 170 Tibetan "rioters" in Lhasa had surrendered by late Wednesday.
Beijing had issued a deadline of midnight on Monday for demonstrators to turn themselves in.
The official Tibet Daily quoted prosecutors in Lhasa as saying that two dozen suspects were arrested for "endangering national security as well as beating, smashing, looting, arson and other grave crimes".
On the political front, Wen Jiabao, China's prime minister, said he may be ready to hold talks with the Dalai Lama.
The Dalai Lama responded that he was willing to meet Chinese officials if he got "concrete indications" that Beijing was ready to talk about the future of Tibet.
China annexed it decades ago and resentment to Chinese rule runs deep.
The Dalai Lama said he has "always been ready" to meet the Chinese leadership, although he acknowledged the prospect of travelling to Beijing at the moment was "not practical".
On the ground, armed police and troops poured into remote towns and villages in Tibet and areas of adjacent provinces to reassert control.
"We saw a big convoy of military vehicles with troops in the back," Georg Blume, a German journalist, told the AFP news agency from Lhasa on Thursday.
"One convoy was about two kilometres long and contained about 200 trucks. Each had 30 soldiers on board so that's about 6,000 military personnel in one convoy."