U2 frontman Bono is urging pro-Tibet campaigners to keep their demonstrations "peaceful" as the Olympic torch relay makes its way around the world.

The Olympic flame was lit in Greece last week and will travel trough 20 countries before it's carried into the Beijing Olympic Games opening ceremony on August 8th.

But the relay has been plagued by controversy, with campaigners contesting China's treatment of pro-independence movements in Tibet.

Protestors clashed with police at the London leg of the relay on Sunday and the flame's subsequent visit to Paris, France, was also marred by violence.

Bono has now voiced his support for the pro-Tibet campaigners but has pleaded with them to keep their protests trouble-free as the torch begins its journey across the U.S.

He says, "I would like a peaceful outcome, for the torch and in Tibet. I hope China takes this opportunity to address the issues.

"It's like waterboarding in the US; it's important to address the issues."