China's attempts to counter international criticisms of the state crackdown on Tibetan unrest received another setback this morning, as a second state media trip to a protest-hit area was interrupted by Tibetan monks.

The authorities have launched a drive to counter what they allege is biased coverage of the unrest and their response by many in the western media. Foreigners are not allowed into Tibet at present and even under normal circumstances journalists are rarely granted permission to travel there.

Reporters attempting to reach other areas of unrest in China have been turned back or ejected by security forces.

Officials arranged for a small group to travel to Xiahe, Gansu province today. The town was the scene of angry protests last month.

But the visit took an unexpected turn as between 15 and 30 lamas, carrying a banned Tibetan flag, burst out of a building at Labrang monastery and rushed across to the group of Chinese and foreign journalists.

"The Dalai Lama has to come back to Tibet. We are not asking for Tibetan independence, we are just asking for human rights, we have no human rights now," one monk told the reporters in Chinese.

According to a Reuters journalist covering the trip, many of the lamas had their heads covered in robes. They said other monks were being held by the authorities and that armed plainclothes agents were stationed throughout Xiahe.

The state news agency Xinhua reported only that a group of monks at the monastery of Labrang in western Gansu province bordering Tibet had interrupted the event, and said the visit resumed soon afterward. It did not mention the tour on its websites.

Last month lamas at the Jokhang temple in Lhasa disrupted the first trip for foreign journalists to Tibet, interrupting a speech on inter-ethnic harmony and telling reporters: "They are tricking you. Don't believe them. They are lying to you."

At a separate press conference in Beijing, Qiangba Puncog, chairman of the Tibet Autonomous Region government, said police had detained 953 people suspected of involvement in last month's violent riots in Lhasa.

But he added that they were "an extremely tiny minority" of Tibetans and that only "an extremely tiny minority" of monks protested.

"They do not, and cannot, represent Tibet and the Tibetan people," he added.

Puncog said prosecutors had also issued arrest warrants for 403 of those detained, a step that generally leads to formal prosecution.

He said 362 people had handed themselves in to police in response to a government ultimatum, but 328 were released on the grounds that their crimes were light and they had a "good attitude" in confessing them. It was unclear if the remaining 34 were included in the tally of detainees.

Police also issued warrants for 93 suspects, 13 of whom have been caught and nine who surrendered themselves.

The government says 22 people, mostly "innocent civilians", died in the Lhasa riots. Independent accounts have described vicious attacks on Han Chinese residents.

The Tibetan government-in-exile alleges the true tally across China is more than 140 with many protesters dying in clashes with security forces.