China has reaffirmed its commitment to take the Olympic torch through Tibet despite strong international pressure.
Tibet's Chinese-backed governor said he would take personal responsibility for the torch's safety and "severely punish" all who tried to obstruct it.
Qiangba Puncog's remarks came as hundreds of pro-Tibet protesters marched through San Francisco ahead of the torch relay there.
Security is tight after chaotic scenes at previous relays in London and Paris.
Earlier Australian Prime Minister Kevin Rudd became the latest Western leader to criticise China's human rights record in Tibet, and called for dialogue between Beijing and the Tibetan spiritual leader, the Dalai Lama.
In a speech to Peking University students on his first visit to China as prime minister, Mr Rudd said it was necessary to recognise there were "significant human rights problems" in the region.
Meanwhile about 15 Tibetan Buddhist monks staged a brief protest in support of the Dalai Lama during an escorted media visit to the Tibetan plateau.
A similar demonstration was staged by monks in Lhasa two weeks ago.
The Olympic torch is expected to reach the Tibetan capital on 20 June, as part of a three month tour of mainland China.
At a news conference in Beijing, Mr Qiangba said he thought the torch relay would be safe and successful.
But he admitted that he did expect trouble from separatists.
"I don't doubt they will create trouble during the torch relay in Tibet," he said.
"If... anyone should attempt to disrupt or undermine the torch relay, they will be dealt with severely according to law."
He said he felt ashamed of those who had caused anti-Chinese unrest in Tibetan areas.
"Tibetan people are modest, good-hearted and grateful," he said.
"These people used the name of Tibet and did something like this - as a Tibetan myself, I feel ashamed for them."
But speaking at a candle-lit vigil on the eve of the San Francisco relay, Hollywood actor Richard Gere said that by parading the torch in Tibet China was trying to give a false picture of peace and harmony there.
"They talk a lot about harmonious society - this is a fake version of harmonious society," he said.
"The game plan of bringing this torch to Tibet, as if it was a harmonious society, is so patently false and insulting to the Tibetans."
Several protests have been planned for the San Francisco relay, which will begin at 1300 (2000GMT) and follow a six-mile (10km) route though the city.
Police say they reserve the right to change the route if necessary.
At Tuesday's vigil, South African Archbishop Desmond Tutu urged world leaders not to go to the Games.
Meanwhile Chinese community representatives called for a peaceful relay and voiced pride over China's hosting of the Olympics.
OLYMPIC TORCH ROUTE
Torch lit in Olympia on 24 March and taken on five-day relay around Greece to Athens
After handover ceremony, it is taken to Beijing on 31 March to begin a journey of 136,800 km (85,000 miles) around the world
Torch arrives in Macau on 3 May. After three-month relay all around China, it arrives in Beijing for opening ceremony on 8 August