KHARTOUM, Sudan - U.S. Deputy Secretary of State Robert Zoellick plans to visit Darfur Friday as part of intensifying diplomatic efforts to halt starvation and armed conflict threatening millions of lives in Sudan's western region.

Darfuri civic leaders who met the State Department's number two official in Khartoum Thursday described a dire situation in their home province.

"All Darfur is a (prison) camp because there is insecurity, starvation," said Mahmoud Mustafa el-Mekki, a senior tribal official.

Madibbo Adam Madibbo, foreign affairs secretary of the Umma Party, Sudan's largest political party, said the authorities could rein in militias who are behind the atrocities and killing in Darfur "but are not willing."

After flying from Khartoum, Zoellick was scheduled to tour Abu Shouk camp near the town of El Fasher after briefings by non-governmental organizations doing humanitarian work there.

When former Secretary of State Colin Powell visited the camp last year its population was roughly 40,000. Now, the figure is twice that.

"There's a possibility of again strengthening the security conditions in Darfur, but I'm focused very heavily now on meeting the near-term humanitarian needs as we approach the rainy season," Zoellick said after talks with government officials Thursday.

"There's a pressing need to get more food into the camps" and Sudanese officials have agreed to speed visas for aid workers trying to cope with the crisis, he said.

Zoellick said Sudan may not have total control over militias behind the atrocities in Darfur but must do more to stop the violence and urged support for an expanded African Union monitoring force in the troubled region.

"There are tribal disputes and militias that may be out of anybody's control, but I think the basic formula here is the government should take every effort it can to stop the militias and certainly shouldn't conduct any violence itself," he told reporters after talks with top Sudanese officials.

"Where the government doesn't feel it can act, then we need to be able to support the AU (African Union) to be able to act."

Zoellick is on a two-day visit to Africa's largest country to put pressure on Sudan to implement a peace deal after a separate North-South conflict in Sudan and end killings in Darfur.

Tens of thousands of people have been killed in the fighting in Darfur and more than 2 million have fled their homes to makeshift camps in the remote desert region.

Zoellick has urged support for expanding the AU forces from 2,000 to 7,500 troops and has worked to have NATO or some of its members, assist with vital services like transport.

The Darfur crisis was triggered in February 2003 when pastoral rebel groups took up arms against the government in a struggle over power and scarce resources. Khartoum retaliated by arming the Janjaweed, a nomadic Arab militia.