Tibetan men and women, who gathered at Thamel -- Kathmandu's tourist hub -- were immediately bundled into waiting police trucks as they marched on the streets on Thursday evening.

"Some 35 Tibetans were rounded up as they staged an anti-China demonstration," police officer Tul Bahadur Karki told AFP at the scene.

Protesters waving flags of Tibetan-government-in-exile and holding portraits of the Dalai Lama shouted, "We want a free Tibet" and "Long live Dalai Lama" as they were driven to one of the police stations in Kathmandu.

About 20 protesters were chased away by police.

Nepal, which has a democratically elected Maoist government, has repeatedly said it will not tolerate anti-China activity as it seeks to preserve friendly ties with its northern neighbour.

Nepalese authorities maintained tight security in Nepal this year to quell possible unrest related to the 50th anniversary of a failed uprising in Tibet which led its spiritual leader, the Dalai Lama, to flee into exile in India.

Sandwiched between India and China, Nepal has upheld Beijing's "One China" policy that views Tibet as an integral part of China.

Nepal is home to around 20,000 exiled Tibetans who began arriving in large numbers in 1959 after the Dalai Lama fled the region.

Worldwide protests erupted last year after China cracked down on demonstrators in Tibet marking the March 10 anniversary of the 1959 uprising.

AFP