China is reportedly moving more security forces into Tibet ahead of the Tibetan New Year and historic anniversaries of protests and exile.
The Dharamsala, India-based Tibetan Center for Human Rights says hundreds of paramilitary forces have arrived ahead of the February 25th Tibetan New Year.
Next month marks the first anniversary of protests and a Chinese crackdown that left at least 19 people dead. And March will be the 50th anniversary of the forced exile of the Dalai Lama following a failed uprising against China.
Chinese authorities in Tibet earlier this week promised to "crush" any signs of support for the Dalai Lama.
China accuses the Dalai Lama of seeking independence for Tibet and provoking mass protests against Chinese rule last year.
The Dalai Lama denies inciting violent protests in China and says he seeks only autonomy for Tibet, where he remains widely revered.
Tibetan rights groups say Chinese security forces have arrested at least 21 people who marched in support of the Dalai Lama over the past week in the southwestern province of Sichuan.
The rights groups say the protesters in the town of Lithang in Sichuan's Garze Tibetan autonomous prefecture were beaten by police before being detained.
Some information for this report provided by Reuters.