The protests began on 10 March - the anniversary of the 1959 Tibetan uprising against Chinese rule - and have gradually escalated.

'Sabotage'

The Dalai Lama spoke in Dharamsala in northern India, where his Free Tibet Movement is based, to reject accusations by Mr Wen of orchestrating the violence.

The Dalai Lama, who in 1989 was awarded the Nobel Peace Prize for his consistent opposition to the use of violence, said that even if "1,000 Tibetans sacrificed their life", this would be "not much help" .

He added: "If things are getting out of control, then the option is to completely resign [as political head]," he said.

A spokesman for the government-in-exile later stressed there was no question of the Dalai Lama stepping down as the spiritual leader of the Tibetan people.

The Dalai Lama reaffirmed that he wanted autonomy for Tibet within China, but not outright independence, which he said was "out of the question".

He also denied Chinese accusations that he instigated the violence.

Earlier, Mr Wen said the Dalai Lama's claim of "cultural genocide" in Tibet was "nothing but lies".

Mr Wen's comments - his first since the violence broke out - came in response to a question by a Western journalist at a news conference following the close of China's parliament.

Mr Wen defended China's handling of the violence, accusing protesters of robbery, arson and violence.

"There is ample fact and plenty of evidence proving this incident was organised, premeditated, masterminded and incited by the Dalai clique," he said.

Mr Wen also said the protesters "wanted to incite the sabotage of the Olympic Games in order to achieve their unspeakable goal". The Games begin in China on 8 August.

Convoys

Large numbers of police are patrolling the streets of Lhasa.

A Chinese deadline for protesters to surrender passed on Monday and there is no immediate word on the military's actions.

The BBC's Daniel Griffiths, who is in western China, said he had seen long convoys of military vehicles heading across the mountains into Tibet.

There are unconfirmed reports of troops sealing off towns.

Demonstrations have spread to Tibetan communities in Gansu and Sichuan provinces.

Police have also stopped BBC journalists from entering the village in which the Dalai Lama was born in north-eastern Tibet.

Tourists flying into Nepal from Lhasa have been giving vivid accounts of the violence.

Swiss tourist, Claud Balsiger, 25, said protesters had told him they were seeking the release of monks, and things "went insane" last Friday after rumours they had been killed.

He said everything that looked Chinese had been attacked or beaten up.

Mr Balsiger also said he had spoken to a Tibetan woman who had lost four family members.

China says Tibet has always been part of its territory but Tibet enjoyed long periods of autonomy before the 20th Century and many Tibetans remain loyal to the Dalai Lama, who fled in 1959.