The United Nations says attacks in Sudan's long-troubled Darfur region have forced more than 45,000 people to flee their homes.
A U.N. spokesman says the violence took place in the southern Darfur region of Um Gunya, with many people fleeing to the state capital, Nyala.
Reports from the scene say the attacks were carried out by Sudanese government forces. But there is no independent confirmation of that.
The U.N. spokesman says violence also has broken out in North Darfur. He said that violence is the result of intercommunal fighting and has forced thousands of people to flee their homes.
U.N. Secretary General Ban Ki-moon said Monday he is deeply concerned about the escalation of violence in Darfur, and he urged all parties to immediately stop hostilities.
Conflict has ravaged Darfur since 2003, when mainly non-Arab rebels took up arms against the Arab-led government, leading to reprisal attacks by government-backed militias.
That conflict has eased in recent years, however battles between rival communities have now become more prevalent.
The United Nations says more than a decade of violence in Darfur has left more than 300,000 people dead and forced close to 2 million civilians from their homes, creating a humanitarian disaster.