The Tibet killings that Fueled Olympic torch protests

The campaigners are protesting against China's human rights record and its crackdown on pro-independence activists in Tibet.

Security forces have locked down Tibet and neighbouring provinces to quell anti-Chinese protests and riots which started in mid-March.

Chinese authorities say 22 died in Lhasa on March 14, but the Tibetan government-in-exile says up to 140 were killed in the riots and the government's ensuing crackdown.

The unrest in the Himalayan region has focused increased international scrutiny and criticism on China in the run-up to this summer's Olympic Games.

China plans to take the Olympic torch to Tibet twice in the months ahead. It will be taken up Everest in early May, and through Lhasa in June.

China says it has ruled Tibet for centuries, although many Tibetans say their homeland was essentially an independent state for most of that time.

Chinese communist troops occupied Tibet in 1951 and Beijing continues to rule the region with a heavy hand.

Beijing has repeatedly accused the Tibetan spiritual leader the Dalai Lama and his supporters of orchestrating the recent violence - the longest and most sustained challenge to China's 57-year rule in the Tibetan region.

Protesters also want to draw attention to China's alleged torture and imprisonment of religious and political dissidents.

China has more executions than any other country in the world, for crimes ranging from fraud to murder. It routinely jails citizens who criticise the regime.

An unprecedented security blanket will be draped across San Francisco for the US leg of the Olympic flame's global relay here Wednesday amid worldwide condemnation of China's crackdown in Tibet and its human rights record ahead of the summer games in Beijing.

Several hundred police officers are expected to line the streets for the appearance of the torch, which has been trailed by protesters since it was lit in Greece a week ago at the start of a 85,000-mile, 21-country journey.