The United States is using private contractors rather than sending American troops to provide logistical support for African forces headed to Sudan's troubled western region of Darfur.

The U.S. government has awarded contracts worth more than $20 million to two companies, the PAE Group and Dyncorp. They will support the anticipated arrival of some 3,500 troops from the African Union in Sudan's Darfur region.

Secretary of State Colin Powell has said he believes genocide is being carried out in Sudan by pro-government militias against African tribes. The U.S. military is advising the African Union troops, but the Bush administration has no plans to send troops to Darfur.

State Department Spokesman Richard Boucher outlined the kind of work the contractors will be doing. "So we have contracted already for building camps, maintaining vehicles and radios, procuring office equipment, providing transport of equipment or personnel," he said.

One of the companies, Dyncorp, already has workers in Afghanistan. Under contract with the State Department, they provide protection to President Hamid Kharzi. Some complaints have been made about the aggressiveness of Dyncorp employees in Afghanistan. Spokesman Boucher says the State Department has discussed the issue with the company.

"We have seen these reports and from time to time heard other reports of aggressive behavior by some of the contractors and we have addressed that issue with the contractors on the ground as well as with Dyncorp management," he said.

Dyncorp has not commented on the charges against it. When asked about the company's role in Sudan, a spokesman said Dyncorp is constrained by what it can say about its work in Sudan because of its contracts with the State Department.