BANGKOK, Oct 5 (Reuters) For years, Western campaigners against Myanmar's ruling generals have struggled to rise above the B-list of world causes.
They looked on as Darfur, climate change and HIV/AIDS grabbed more headlines, more cash, lured marquee celebrity activists and caught the ear of world leaders. That all changed last week.
As images of the bloody crackdown against anti-junta protesters fuelled global outrage, British Prime Minister Gordon Brown called a London-based activist group to offer his help.
''So far this year, the British Foreign Office hadn't even bothered to reply to our letters; now the Prime Minister is on the phone to us,'' said Mark Farmaner, spokesman for the Burma Campaign UK.
''The impact for us has been incredible.'' In the first days of the crackdown, in which diplomats believe many more than junta's admitted 10 people were killed, Farmaner's group received up to 600 phone calls a day from journalists, crashing its voice mail system.
''Our printer broke. Laptop died. Even the camp bed I had in the office fell apart,'' he said.
Their Web site, www.burmacampaign.org.uk, has had more hits in the past week than over an entire year. An on-line appeal for donations netted 20,000 dollar in the first week, equal to six months' normal donations.
''Up until now we had been having a difficult year financially, with donations lower than usual,'' Farmaner said.
International sympathy for the Myanmar protesters -- the junta admits more than 1,400 are still detained -- has energised a street campaign that never gained traction despite the iconic image of detained opposition leader Aung San Suu Kyi, often described as Asia's Nelson Mandela.
In some Western and Asian capitals, thousands have marched to the embassies of Myanmar and China, seen as a key backer of the regime and its defender in the UN Security Council, where only handfuls of diehard demonstrators had gone before.
''People are really angry at China and unless they change their stance now, I believe there may be a real Olympic boycott,'' said Jeremy Woodrum of the U.S. Campaign for Burma, which organised protests at China's embassy in Washington last week.
Activists hope to crank up the pressure on Saturday with a ''Global Day of Action'' involving marches and rallies in 41 cities across Asia, Europe and North America.
The Internet is playing an even bigger role in rallying opposition. Some 300,000 people have joined the ''Support the monks protest in Burma'' campaign on the social networking Facebook site since it was launched on September 19.
''It is essential that once the world's media turns its attention elsewhere, Gordon Brown and other world leaders remain actively engaged in driving forward international action,'' said Farmaner.
Activists have struggled to lure Hollywood celebrities to the cause as they try to copy a campaign against rights abuses in the Darfur region of Sudan, which has drawn such well-known names as George Clooney and Matt Damon.
But last month, more than 25 celebrities including Jennifer Aniston, Owen Wilson, Anjelica Huston and Dustin Hoffman petitioned UN Secretary-General Ban Ki-moon to push for stronger action against the generals.
Action star Sylvester Stallone's latest ''Rambo'' movie, which pits Vietnam veteran John Rambo against the might of the Myanmar army, is bound to help activists keep up the momentum when it is released in January.
Some analysts doubt the street marches, Internet campaigns and celebrity appeals will have much of an impact.
''They are good people I'm sure, and we all want the same thing out of that society, but that doesn't mean they can get it the way they are going,'' said David Steinberg, a Myanmar expert at Georgetown University.
However, some activists have drawn inspiration from past human rights campaigns, including the struggle against apartheid in South Africa which ended with democratic elections in 1994.
At the height of the Myanmar monks' protests last month, Archbishop and Nobel Peace Prize winner Desmond Tutu said it reminded him of ''the rolling mass action that eventually toppled apartheid''.
The 1976 Soweto uprising, in which hundreds of students were shot by security forces, is often viewed as the beginning of the end of apartheid, even though it would take nearly 30 years.
''These things ebb and flow, but for the next few years we have a huge surge of support that we have to keep mobilising,'' said Debbie Stothard of the Myanmar rights group ALTSEAN.
''The struggle is not yet over. This is one milestone.'' REUTERS SYU SSC1340