As Tibetan protesters continued to rally and demonstrate against Chinese rule, a Foreign Office minister delivered Britain's strongest condemnation yet of Beijing's handling of the crisis.

Lord Malloch-Brown called on UK athletes at this year's Beijing Olympics to "speak the truth" about what was happening in the country. His surprise intervention exposed growing tensions in British government ranks over how to respond to the unrest in Tibet and China's human rights record.

Gordon Brown had earlier risked the anger of Beijing by announcing he would meet the Dalai Lama, the exiled Tibetan spiritual leader, when he visits Britain in May. But the Prime Minister's instinctive preference for cautious diplomacy was undermined by his minister's strongly-worded warning to Beijing not to resort to brute force against the demonstrators.

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Lord Malloch-Brown said: "China will damage its own interests and the reputation of the event, perhaps irrevocably, if there is extensive violence."

He said: "We will expect to see our athletes respect both the values of Britain – courtesy and respect for the country where the Games are – but also that supremely important value of speaking the truth as they see it."

He made it clear he did not support a boycott of the Olympics. But added: "We, however, as a Government, remain extremely concerned about the situation in Tibet. We urge restraint by all sides."

Mr Brown has always been much more restrained in his language over Tibet, perhaps mindful that a full-blown crisis over the Beijing Olympics could have a knock-on effect on the London games in four years' time.

The Prime Minister disclosed that the Beijing government had told him it was prepared to hold talks with the Dalai Lama. He revealed yesterday in the Commons that he had spoken with the Chinese premier Wen Jiabao to urge the authorities to show restraint in dealing with protesters. "I made it absolutely clear that there had to be an end to violence in Tibet," Mr Brown said.

"The premier told me that, subject to two things that the Dalai Lama has already said – that he does not support the total independence of Tibet, and that he renounces violence – that he would be prepared to enter into dialogue with the Dalai Lama."

Lord Malloch-Brown's intervention on the Olympics came as Beijing vowed to take the Olympic torch to Tibet despite the provocation that represents.

"The situation in Tibet has essentially stabilised, the Olympic torch relay will proceed as scheduled," Jiang Xiaoyu, executive vice-president of the Beijing Organising Committee for the Olympic Games, told reporters.

The prospect of talks between the Chinese government and the Dalai Lama came as demonstrations continued in Tibet, despite a crackdown by Beijing that has killed an unknown number of people. Whatever undertaking the Chinese premier may have given Mr Brown, in public officials continued to describe the Dalai Lama as a "wolf in monk's robes, a devil with a human face but the heart of a beast".

In Dharamsala – home to the Tibetan exiles – hundreds of Buddhist monks and civilians have been marching in protest: "We are showing the world what is happening in Tibet," said one monk, Tashi. "If Tibet is lost, then the world will lose peace and compassion."