Dozens of Tibetan monks and nuns clashed with police Wednesday afternoon around the Chinese visa office premises in central Kathmandu.

The protesters, who were wearing Free-Tibet T-shirts and chanting anti-China slogans, tried to storm the office while police used force to stop them.

Police grabbed at least 15 of the protesters by their collars, dragged them along the blacktopped street, hurled them into patrol vans and took them into detention.

Earlier, in Kathmandu's Bouddha area, thousands of Tibetans held prayers in a monastery before beginning a protest rally and heard a message from the Dalai Lama read out by his representative on the 51st anniversary of the failed uprising in Tibet that forced the Dalai Lama into exile.

The situation turned hostile after hundreds of security personnel blocked exits from the area, fearing the Tibetans would march towards central parts of the Nepalese capital.

Bouddha Police Chief Govinda Ram Pariyar said it was a preemptive measure, but the Tibetans, who had refrained from provoking police until then, chanted anti-China slogans after police blocked the exits from the area.

Pariyar said a foreigner who was among five arrested in Bouddha Wednesday morning is a French national, but he would not divulge her name.