Police have arrested George Clooney during a protest outside the Sudanese embassy in Washington DC.

The actor, who is president of United to End Genocide, was arrested and handcuffed along with several Democrat politicians and other human rights and faith leaders for civil disobedience.

The campaigners were protesting the humanitarian emergency that is reportedly threatening the lives of 500,000 people.

After speaking on the steps of the embassy to hundreds of activists, members of Congress and activist leaders were warned by police to leave the scene. When they refused, police arrested them.

Clooney, his father, Nick - a well known radio broadcaster in the US - and others, including Democratic politician Jim Moran of Virginia and civil rights leader Ben Jealous, were held after being warned three times not to cross a police line outside the embassy.

Their hands were tied with plastic cables and they were put into a US Secret Service van.

Asked about his arrest as he was led away, Clooney told a reporter: "It is a pretty humiliating thing, quite honestly."

"He feels good about the arrest. It was expected," said Sky News US correspondent Greg Milam. "It was what they would have wanted to happen."

"He clearly feels this is the way to get the message out there."

"He may think Sudan doesn't get enough attention and, being George Clooney, he knows how to get it."

Swarmed by journalists, flashing cameras and TV crews, Clooney said earlier that he hoped to draw more attention to the issue and that if action is not taken in the next three to four months "we're going to have a real humanitarian disaster."

"We need humanitarian aid to be allowed into the Sudan before it becomes the worst humanitarian crisis in the world - immediately," Clooney said to cheering supporters shortly before his arrest.

"The second thing we are here to ask is a very simple thing - it's for the government in Khartoum to stop randomly killing its own innocent men, women and children," continued the 50-year-old star of The Descendants.

"Stop raping them, and stop starving them. That's all we ask," added the long-time activist for human rights in Sudan.

The protesters were demanding that Sudan's President Omar al Bashir immediately end the blockade that they said is preventing food and humanitarian aid from reaching the people of Sudan's Nuba Mountains and Blue Nile regions.

They added that Bashir's forces had created the dire food shortage in the region by bombing fields and preventing villagers from planting crops in July and August last year.

John Prendergast, co-founder of the campaign group Enough Project, said: "George Clooney and I just returned from the Nuba Mountains, where the Sudan government regularly bombs civilians and blocks humanitarian aid to the war-torn regions along the border with South Sudan.

"It is urgent that the Khartoum government allow aid access."

"We are protesting to make sure the Sudanese government knows that the world is watching," said congressman Jim McGovern, who is also believed to have been arrested.

"The United States Congress is watching. And we will be back again and again until they stop using food as a weapon; stop slaughtering innocent men, women and children; and stop spitting in the face of the world community."