A day of protests marked the 49th anniversary of the Dalai Lama's escape from Tibet after a failed uprising against Chinese rule.
More than 100 Tibetan exiles in India set out on a march from Dharamsala to Tibet.
They were protesting against China's hosting of the Olympic Games later this year.
But police in Dharamsala said they were prevented from leaving the area.
Organisers say they represent tens of thousands of Tibetan exiles, and want to draw attention to what they see as Chinese suppression of Tibetan identity.
The Nepalese capital, Kathmandu, also saw clashes between police and Tibetan protesters...
... while Greek police intervened when Tibetan athletes began protesting at the site of Olympia, the birthplace of the ancient Olympic Games.