Chinese security forces and police manned checkpoints and patrolled cities around Tibet on the first anniversary of violent anti-Chinese protests Saturday.
The Hong Kong-based South China Morning Post reported Chinese authorities were conducting door-to-door searches to round up what the newspaper referred to as "suspicious" people.
Tibet's Communist Party secretary, Zhang Qingli, called on troops to "foil" what he called the "Dalai clique" - referring to followers of Tibet's exiled spiritual leader, the Dalai Lama.
Meanwhile, hundreds of protesters marched through the Taiwanese capital of Taipei carrying the Tibetan flag and pictures of the Dalai Lama and chanting "Free Tibet." And Nepalese police detained at least two protesters from Britain and Norway for staging a pro-Tibet protest near the Chinese visa office in the capital of Katmandu.
Four days of protests calling for the return of the Dalai Lama spread from the Tibetan capital of Lhasa to Tibetan regions of China before turning violent on March 14 of last year.
China launched crackdowns and said that about 20 people were killed. But Tibetan exiles and human rights groups say about 200 Tibetans died.
The U.S.-based International Campaign for Tibet says about 1,200 Tibetans remain missing.
On Friday, China issued its strongest recent criticism of the Dalai Lama, calling him a political exile - not a religious figure.
Chinese Premier Wen Jiabao said Tibet's government-in-exile is theocratic and illegal, and that it is under the direct leadership of the Dalai Lama.
Premier Wen's remarks came at the end of a week that marks the 50th anniversary of a failed uprising in Tibet against Chinese rule. The Dalai Lama fled to India after the uprising. Tibet's government in exile is based in Dharamsala, India.
Some information for this report was provided by AP and Reuters.