Officials in Sudan are denying rebel claims that the government has launched new attacks in violation of the Darfur peace agreement.
Multiple reports from the region say government troops and Arab militias attacked sites in North and South Darfur over the last several days. Details are sketchy, but witnesses say at least 20 people have been killed in the fighting.
Sudanese officials say allegations of army involvement are untrue.
Darfur's largest rebel group signed a deal with the government on May 5 to end three years of fighting in the region. Two smaller rebel groups have refused to sign.
Meanwhile, two United Nations envoys are due to arrive in Khartoum on Tuesday for talks with the government about the planned deployment of U.N. peacekeepers to Darfur.
Sudan has yet to approve the U.N. mission, saying it wants more input into the size and mandate of the force.
An African Union force has been unable to stop the fighting in Darfur, which has killed at least 180,000 people.
Some information for this report was provided by AP.
