DAKAR, Senegal (AP) _ A small number of U.S. troops have been working with the African Union military observer mission in Sudan's troubled Darfur region, the State Department said Wednesday, highlighting the U.S. role in peace efforts.

In Washington, spokesman Richard Boucher said perhaps ``two or four'' troops have joined the cease-fire monitors and were in place when Secretary of State Colin Powell met with African Union officials during a recent visit.

``The United States has been a very strong supporter. We have been there,'' Boucher said.

The United States has sent $6.8 million to support the African Union's expanded deployment, and has another $25.5 million ready.

Washington has been a leader in pressing Sudan's government to stop 19 months of violence in Darfur, where pro-government Arab militia _ known as the Janjaweed _ are accused of leading a bloody campaign to drive out non-Arab farmers.

Both the United States and Europe have pushed African governments to take a lead role in any military action to stop the violence.

So far, about 80 AU military observers, supported by 300 troops of the 52-nation African Union bloc, currently are deployed to monitor a largely failed April cease-fire.

Powell discussed the U.S. participation on Friday, in a speech hosted by Georgetown University.

``And so we believe the best solution is to continue to press the Sudanese to bring the Janjaweed and the other militias under control and to meet their responsibilities. And we'll help them,'' Powell said.

Powell also said that genocide ``had been committed'' in Darfur by Sudan's government and allied militias.

(Corrects American to African in first graf.)