Tibetan monks on Thursday embarrassed China by staging a protest and voicing their support for the Dalai Lama in front of visiting foreign reporters in Lhasa.

The protest, defying tight security, came as China took some of the Beijing-based foreign correspondents on an escorted tour of riot-hit Lhasa, the Tibetan capital, media reports said.

About 30 monks shouted pro-Tibetan slogans and in support of the Dalai Lama as journalists toured the Jokhang Temple, one of Tibet's holiest shrines.

One monk shouted, "Tibet is not free, Tibet is not free" before he started to cry, an AP journalist at the scene reported.

Foreign journalists have largely been prevented from covering the unrest, the biggest since 1989. However, China on Wednesday allowed a group of reporters into Lhasa for a three-day escorted visit.

The visit to Lhasa is the first by foreign journalists since violent pro-independence protests erupted there two weeks ago.

China has accused the Dalai Lama of "masterminding" the protests aimed at "sabotaging" the Beijing Olympics in August.

The protests began on March 10 and developed into violent rioting in Lhasa before spreading to neighbouring regions.

China says 20 people were killed by rioters. The Tibetan government-in-exile maintains that about 140 people have been killed in a crackdown by Chinese security forces.