At least nine people were killed and 11 injured in Burma today when soldiers opened fire on thousands of anti-government protestors.

Among those killed was a Japanese journalist covering the pro-democracy demonstrations in Rangoon, the country's largest city.

Despite threats from soldiers and armed police, more than 70,000 people gathered for a 10th consecutive day of marches against Burma's brutal military leadership.

Britain's ambassador to Burma, Mark Canning, said the authorities "ratcheted up" their response today in an attempt to "scare and intimidate" the protesters.

He said large parts of Rangoon were barricaded off, including the golden Shwedagon Pagoda, but many demonstrators still took to the streets.

Mr Canning said there were more civilians than monks and there was a greater level of violence than on the previous marches.

The ambassador told BBC Radio 4's The World At One: "I don't know whether they are going to come out tomorrow.

"If people are willing to do what they did today to face down the guns, to risk being beaten and killed, they are being driven by very serious hardship.

"That's what's been driving this from the outset, the extreme economic conditions that people are facing."

Hundreds of Burmese exiles and British human rights campaigners demanded an end to the murderous repression at a demonstration in London today.

Gathering outside Burma's embassy in Mayfair, they waved banners, chanted slogans, sang protest songs and prayed for peace.

Many wore red headbands emblazoned with the golden fighting peacock, a symbol of the Burmese democracy movement.

Several held up pictures of the street protests in Rangoon, while others waved images of detained opposition leader Aung San Suu Kyi.

Demonstration organiser Ko Aung, of the Burmese Democratic Movement Association, told the protesters it was time for the international community to take action.

He said: "Inside Burma people are now peacefully protesting and are killed by the oppressive regime that has ruled my country for more than four decades."

To loud cheers and applause, he added: "They have been suffering for a long, long time. So, international community, what are you waiting for?"

The United Nations Security Council yesterday issued a statement urging the Burmese government to exercise restraint towards peaceful protesters, but has so far held back from more concrete action.

Today's demonstration in London also included a large contingent from human rights group Amnesty International, whose UK director, Kate Allen, addressed the crowd.

She said what was happening in Burma was "deeply outrageous" but warned that the "eyes of the world" were on the military junta's actions.

"That government is on a precipice, and we at Amnesty join in with many others to demand that they pay attention to the human rights of the people of their country.

"We want the United Nations to put this issue at the forefront of their concerns," she added.

Shadow international development secretary Andrew Mitchell, who met a member of Burma's ruling junta on a visit to the country in March, also attended the rally.

He received cheers when he said the "tyrannical regime" should be "held to account" and possibly referred to the International Criminal Court.

About 200 of the protesters later reassembled for a second demonstration outside the Chinese embassy in London, organiser Kyaw Zwa said.

China - Burma's main trading partner and arms supplier - has rejected calls for sanctions against the regime, citing its policy of non-interference in other countries' affairs.

Japanese video journalist Kenji Nagai, 50, who was covering the protests in Burma for Japanese video news agency APF News, was among those killed in Rangoon today.

Troops in at least four locations in the city fired into crowds after thousands of protesters ignored orders to disband, witnesses and diplomats said.

Before dawn the authorities raided several monasteries linked to the pro-democracy movement, reportedly arresting over 100 monks.

Security forces also arrested Myint Thein, spokesman for Ms Suu Kyi's political party, family members said.

In Mandalay, Burma's second-largest city, five army trucks loaded with soldiers and three fire trucks were seen driving into the Mahamuni Pagoda, where hundreds of monks were locked inside by security forces.

Burma's state-run newspaper today blamed "saboteurs inside and outside the nation" for causing the protests in Rangoon, and said the demonstrations were much smaller than the foreign media were reporting.

The Burmese government said one man was killed in Rangoon yesterday when police opened fire during the ninth consecutive day of demonstrations, but dissidents outside Burma reported receiving news of up to eight deaths.

Led by thousands of Buddhist monks in maroon robes, the Burmese protesters have been demanding the release of political activists and economic reforms in the impoverished nation.

The crisis began on August 19 with protests over a fuel price hike, but has been swelled by pent-up opposition to years of harsh military rule.

In the US, President George Bush urged all nations which have influence with the regime to support the aspirations of the Burmese people and to call for an end to the violence.

He said: "The world is watching the people of Burma take to the streets to demand their freedom, and the American people stand in solidarity with these brave individuals.

"We feel admiration and compassion for the monks and peaceful protesters calling for democracy.

"Every civilised nation has a responsibility to stand up for people suffering under a brutal military regime like the one that has ruled Burma for too long.

"I call on all nations that have influence with the regime to join us in supporting the aspirations of the Burmese people and to tell the Burmese junta to cease using force on its own people, who are peacefully expressing their desire for change.

"By its own account, the junta has already killed at least nine non-violent demonstrators, and many others have been injured and arrested as they seek to express their views peacefully.

"I urge the Burmese soldiers and police not to use force on their fellow citizens. I call on those who embrace the values of human rights and freedom to support the legitimate demands of the Burmese people."

Historian Simon Schama tonight called for a mass boycott of next year's Olympic Games in China.

"The Olympics are the only leverage we have," he said on BBC's Question Time.

"If China vetoes serious discussion of measures to be taken at the United Nations there should be a mass boycott of the Olympic Games.

"It's as simple as that. That is our major point of leverage."

Skills Secretary John Denham, who also appeared on the show, warned against taking "knee-jerk decisions".

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