Fu Hongyu, Communist Party commissar of the Ministry of Public Security's Border Control Department, told Xinhua news agency on Monday that the extra security would "fully protect the stability of Tibet's frontier region".

"To address stability protection in Tibet, we have deployed troops to strengthen controls along the Tibetan (international) frontier at points of entry and on key sectors and roads," said Fu.

China shares a border in the Himalayan region with India, Nepal and Bhutan. For many years Tibetans have crossed back and forth, some with official approval and some to study in Buddhist monasteries run by exiled monks.

Fu's comments were another official warning against groups that may seek to use this month to show discontent with Chinese rule in Tibet, 50 years after the region's Buddhist leader, the Dalai Lama, fled across the mountain border into north India after a failed insurrection against Chinese rule.

The anniversary of the Dalai Lama's flight falls on Tuesday.

A year ago, monk-led protests against Chinese rule in Tibet's regional capital, Lhasa, gave way to rioting on March 14 when a Tibetan crowd attacked shops run by Han Chinese and Hui Muslims, killing 19 people. The unrest and subsequent security crackdown spread across Tibetan areas.

Groups abroad demanding Tibetan self-rule have said more than 200 Tibetans may have died in region-wide clashes. Chinese officials have rejected these claims and said they used minimal force.

A German newspaper, the Frankfurter Rundschau, on Friday quoted the Dalai Lama as saying Tibet was very tense and that there could be "an explosion of violence" at any time.

China says that the Dalai Lama's "clique" instigated the unrest last year and it calls him a separatist using religion to press for an independent Tibet. But the 73-year-old monk says he opposes violence and wants only high-level autonomy, under Chinese sovereignty, for his homeland.