Tibetan activists vowed to keep up their protests during the Olympic torch relay, calling on British athletes participating in the event to speak out against human rights abuses by the Chinese government when the political and sporting jamboree visits London next month.

Their call came as the Foreign Office condemned Beijing for its continuing "violation" of human rights, noting that China executed more people than any other country last year. Speaking at yesterday's launch of the annual human rights report, the Foreign Secretary, David Miliband, said that global concern about China's crackdown in Tibet was "justified and proper".

The latest round of anti-China protests began in the Tibetan capital, Lhasa, on 10 March – the anniversary of a failed uprising against Chinese rule in 1959. They turned violent four days later and sparked demonstrations among Tibetans in three neighbouring provinces of China.

Two more people died in clashes between Chinese police and Tibetans yesterday. Human rights groups say 140 people have been killed but the Chinese government puts the number of dead at 22.

Yesterday, the French President Nicholas Sarkozy, who arrives in Britain today for a state visit, became the first world leader to threaten Beijing with an Olympic walkout in protest at the crackdown. Asked whether he supported a boycott of the opening ceremony in August, M. Sarkozy said he could "not close the door to any possibility". His comment is certain to embarrass Chinese officials who are desperately trying to prevent unrest in Tibet from detracting from the Games. They are billing the 130-day, 137,000km Olympic torch relay as a "journey of harmony" that will enhance mutual understanding and friendship between nations, but the route has taken on increasingly political overtones.

On Monday, pro-Tibet demonstrators disrupted the Olympic torch-lighting ceremony in Greece ahead of the Beijing Games. The torch will be carried through 20 countries, including Britain, before returning to Beijing on 8 August. Activists along the route have threatened to demonstrate against China's action in Tibet and its support for the oppressive regimes in Burma and Sudan.

A Thai athlete, Narisa Chakrabongse, has already pulled out of the relay in Bangkok and campaigners have urged other Olympic athletes to do likewise or use their roles as torch-bearers to highlight human rights abuses by China.

"It would be an incredible show of support to the Tibetan people if torch-bearers and athletes spoke out," said Lhadon Tethong, of the Students for a Free Tibet group. "Most will stay quiet but there will always be a few people brave enough to say what they really believe."

The torch arrives in the UK on 6 April and will be carried through London by 80 people, including the Olympic gold medallist Dame Kelly Holmes and the newsreader Sir Trevor McDonald.

Anne Holmes, of Free Tibet UK, said participants in the relay had a "moral obligation" to speak out against human rights abuses. "Nothing would please me more than to see someone like Sir Trevor McDonald running the torch relay while wearing a Free Tibet T-shirt," she added.

Last night, China condemned the protest in Olympia and urged foreign governments to ensure that future demonstrations did not halt the torch relay. "Any act to disrupt the Olympic relay is shameful and unpopular," said Qin Gang, a spokesman for the government. "We also believe competent authorities in countries which the torch relay will pass have the obligation to ensure a smooth relay."

Yesterday, Tibetan exiles carried a symbolic "Olympic" flame through the northern Indian city of Dharmsala to begin their own torch procession which will end in Tibet on the day the Summer Games opens in Beijing.

Meanwhile, the European Union, the US, Australia and Canada all called on China to stop using force against the Tibetan people. However, the White House said President George Bush still planned to attend the opening of the Games, while the British Government said Prime Minister Gordon Brown would still be going to the closing ceremony.