The arrests and promises of tough reprisals indicate the Chinese government will move to end the protests, despite calls from abroad to exercise restraint and warnings that heavy-handed repression could mar this summer's Olympic Games in Beijing, The Washington Post reported.

In a broadcast announcement, the government gave protesters until midnight Monday to turn themselves in, after which they were threatened with arrest. However, Urgen Tenzin, executive director of the India-based Tibetan Center for Human Rights and Democracy, told The Post he learned about 600 Tibetans were arrested before nightfall by a police sweep that lasted most of the day.

"We must give them tit for tat and firmly counterattack," said an editorial the Tibet Daily, the Communist Party's official newspaper in Lhasa.

Champa Phuntsok, a Tibetan who is the territory's second-ranking official under party secretary Zhang Qingli, said 13 people died during the riots, raising by three the previous official toll. Most deaths occurred Friday, when maroon-robed monks and Tibetan youths dressed in street clothes set fires, looted shops and beat Chinese.