ROME (Reuters) - Hollywood actors George Clooney and Don Cheadle received an award from Nobel peace prize laureates on Thursday for their campaign to help the people of Sudan's Darfur region after 4-1/2 years of war.

Together with Brad Pitt, Clooney and Cheadle -- co-stars in "Ocean's Thirteen" -- have used their celebrity status to raise money for refugees through their "Not On Our Watch" charity, and make sure Darfur's "continuing carnage" is not forgotten.

Experts estimate 200,000 people have been killed and 2.5 million uprooted in the conflict pitting mostly non-Arab rebel groups against the Khartoum government and Arab militia since 2003.

Ceasefires have been agreed only to fall apart, and plans to send 26,000 United Nations peacekeepers have been thrown into doubt because of restrictions imposed by Khartoum and the failure by Western states to provide helicopters.

"Don and I... stand here before you as failures," Clooney said, comparing his efforts to the achievements of the Nobel laureates attending the Peace Summit Award ceremony in Rome, including former Soviet President Mikhail Gorbachev and the Dalai Lama.

"The simple truth is that when it comes to the atrocities in Darfur those people are not better off now than they were years ago. The murders continue, the rapes continue and some two and a half million refugees are yet to go home," he said.

"Some day this will all end, and whether all of us succeed or not it will end some day. And when they write about this, the question will be asked: where was the rest of the world? And the answer will be: it just wasn't a priority."

Cheadle, who earned an Oscar nomination for his role in "Hotel Rwanda", about a hotel manager struggling to save lives during the 1994 genocide, said the award was an "inspiration to keep up the fight".

Earlier this year Clooney, Cheadle and Pitt raised $10 million for Darfur at the Cannes film festival. Clooney and Cheadle also feature in a recently released documentary on the conflict, "Darfur Now".