The Bush administration said on Saturday it was "very concerned" about the outbreak of violence in Sudan between Darfur rebels and government troops and urged both sides to exercise restraint.
Rebels fought Sudanese troops in a suburb of the capital, Khartoum, in an effort to seize power but the government said the attack had been defeated.
"We are very concerned about the situation," White House spokesman Gordon Johndroe said in Texas where U.S. President George W Bush was attending his daughter Jenna's wedding.
"We would urge that both sides cease hostilities, whether it is the rebel group or any response from the government. We want to see a calm and order restored," Johndroe said.
International experts estimate some 200,000 people have died and 2.5 million been made homeless in Darfur since mostly non-Arab rebels took up arms, accusing the central government of neglect.
The United States has labeled the conflict in Darfur as genocide, a charge the Sudanese government has rejected. The White House spokesman said the US Embassy there was monitoring the latest violence closely.