Rebels shelled the main city of Sudan's oil-producing South Kordofan state, hitting the central market, a school and a local police station, authorities said.
An official in the Sudanese border state of South Kordofan said six people were killed and more than 20 others were injured in rebel mortar attacks.
The U.N. high commissioner for Human Rights said orders issued by a Sudanese official to "clean" an area of rebels could be considered criminal.
Military forces freed 14 of 29 Chinese workers kidnapped during the weekend in Sudan's South Kordofan province, the governor of South Darfur state said Monday.
Authorities in the war-torn Sudanese state of South Kordofan said rebel forces suffered huge losses, though the rebels have denied the claims.
South Sudan's ruling party says the election of a man wanted by the International Criminal Court in The Hague, Netherlands, for war crimes was rigged.
Sudan is violating international law by failing to arrest Darfur war crimes suspects, the U.N. Security Council charges.
The prosecutor of the International Criminal Court in Geneva said he will finalize two investigations into Darfur war crimes by the end of the year.
Sudan has nominated suspected war criminal Ahmed Haroun as co-chair of a committee responsible for investigating human rights complaints in Darfur.
The government of Sudan rejected arrest warrants issued Wednesday by the International Criminal Court at The Hague for two men involved in the Darfur crisis.