Determined to prevent anti-China demonstrations in Tibet Wednesday, the 51st anniversary of a failed Tibetan uprising against Chinese annexation, Beijing has snapped most links between the former Buddhist kingdom and its neighbour Nepal.

The bridge connecting northern Nepal with Tibet - the Friendship Bridge - has been effectively closed by the Chinese authorities, rights body International Campaign for Tibet (ICT) said in a statement, while flights between Kathmandu and Lhasa, the Tibetan capital, have been grounded since Friday.

Travel agents in Nepal have also been warned that tourists may not be allowed to enter Tibet for several days after March 10, ICT said.

On Monday, security officials from both Nepal and China held talks in Khasa town on the Nepal-Tibet border to discuss how to beef up security along the border between the two countries.

China suspects Tibetan dissidents will be pushed to Nepal from India with Indian and American aid to keep up rallies for a 'Free Tibet'.

It has been urging Nepal to regulate its nearly 1,800km open border with India but the demand is yet to be fulfilled by the Nepal government.

Nepal however has beefed up security on its own territory to stop protests or even large-scale prayers in memory of the Tibetans who died in the uprising in Tibet in 1959 as well as hundreds of people who were arrested and went missing after demonstrations in Tibet in 2008.

The Dalai Lama's unofficial representative Thinley Gyatso was arrested by Nepal police Sunday and released after a threatening interrogation as well as warning not to take part in any protests.

Security has also been beefed up around the Chinese Embassy in Kathmandu and the Tibet visa office.

Since last month, police have been ordered to raid houses and hotels in the area around the Tibetan religious shrine Boudhanath, a major pilgrimage destination for Tibetan Buddhists.

There have also been pre-emptive arrests of Tibetans, ID checks and house searches as well as large-scale police deployment in Tibetan communities.

The harassment and extortion has created a sense of fear and insecurity among long-staying Tibetan refugees in Nepal with police threats of deportation.

As part of its carrot and stick policy, China has also stepped up offers of assistance to Nepal.

Nepal's Defence Minister Bidya Bhandari is leaving for China on an eight-day visit March 26 to discuss military assistance.