Fifteen boys and 5 girls were arrested, weeks after Nepal assured Beijing that it would crack down on anti-China activities from its soil.
The teenagers were travelling on foot and were without valid travel documents, the police said.
"We are unable to establish their identities as they cannot speak Nepali Language," Birkha Bahadur Rawal, DSP of Bajura was quoted as saying by Himalayan Times.
These Tibetans were arrested from Bauli of Bajura district on their way to Dharamshala via Kathmandu to meet the Dalai Lama, according to the police.
They had reached the district after 17-days of walk.
The police said that it was difficult to establish their identity as they do not speak Nepali or English.
The arrested Tibetan nationals will be sent to the Immigration Department in Kathmandu for taking further action in the matter, police said.
Every year some 2,500 Tibetans illegally enter Nepal crossing Tibetan border on their way to Dharamshala to meet the Dalai Lama. Nepal houses more than 20,000 Tibetan exiles.
Nepal has promised China not to allow "anti-Chinese activities" from its soil as a visiting top-level delegation from the Communist nation recently announced a USD 50-million aid package for the country.
China is a major donor to Nepal. Beijing has increased pressure on Nepal to check the flow of Tibetans fleeing their homeland.
