Nepal, under increasing pressure from China, was cracking down on Tibetan refugees despite centuries of shared culture with Tibet.
Pre-emptive arrests of Tibetans, ID checks and house searches by authorities were contributing to a widespread sense of fear and insecurity among the exiles.
Nepali officials did not comment immediately but the impoverished nation considers Tibet as part of China, a key trading partner and aid donor.
Kathmandu says Tibetan refugees are free to live in Nepal but cannot carry out any anti-China activities.
Nepal is home to more than 20,000 Tibetans who fled the Himalayan region after a failed uprising against Chinese rule in 1959.
About 2,500 flee Tibet every year and come to Nepal on way to India where their temporal leader, the Dalai Lama, lives.