Sudanese police were killed in fighting with Darfuri rebels on Wednesday as analysts expected a spike in clashes ahead of a referendum that may partition Sudan.
Police clashed with rebels of the Justice and Equality Movement (JEM) in south Darfur after the rebels attacked a fuel and supplies convoy, the interior ministry said.
"The Central Reserve Forces lost a number of martyrs and is still pursuing (the rebels) after they suffered great losses and fled," a statement said.
Suleiman Sandal, head of JEM's military operations, said police, supported by troops, attacked their positions and claimed that the rebels killed between 50 and 70 soldiers.
The joint United Nations-African Union peacekeeping mission in Darfur called on the rebels and the government to stop the fighting.
"UNAMID is concerned about the heightened military condition on the ground. There have been other incidents recently and UNAMID calls on all the parties to refrain from the use of war," the head of the mission, Ibrahim Gambari, said in a statement.
Khartoum earlier this year but the talks foundered amid renewed fighting.
Darfur has been gripped by a civil war since 2003 that has killed 300,000 people and displaced another 2.7 million, according to UN figures. Khartoum says 10,000 people have died in the conflict.