|Darfur has been volatile since fighting between government forces and rebels began in 2003 [EPA]
Thirteen Sudanese police officers have been killed in clashes with an armed gang as they tried to rescue three hostages in the Darfur region, officials say.
A police spokesman said on Friday that 30 others had been injured in the clashes on Thursday.
"What happened yesterday involved an armed gang, not a rebel group," Ahmed al-Tughani told the AFP news agency.
"The police tried to release three hostages in eastern Jebel Marra. Clashes broke out with the gang and we lost 13 men and 30 others were wounded".
He was unable to provide further details, including the identity of the hostages.
There has been a wave of kidnappings for ransom in Darfur since March 2009 when the International Criminal Court indicted Sudanese President Omar al-Bashir for alleged war crimes and crimes against humanity in the region.
Around 30 foreigners have been kidnapped in Darfur since the indictment, with most of them released unharmed a few days later.
But three Bulgarian helicopter pilots, kidnapped in Darfur while working under a UN contract, were freed in June after spending 145 days in captivity.
Last month, Italian humanitarian worker Francesco Azzara, who worked at a child-care centre in Nyala, was abducted as he was driving to the airport.
Abdel Hamid Kasha, the governor of South Darfur, denied a report by Sudan's al-Ahdath newspaper that one
of the hostages was the Italian aid worker.
"The Italian is another case," he told Reuters news agency.
Darfur erupted into conflict in 2003, when the Arab-dominated Khartoum government launched an offensive against non-Arab rebels.
At least 300,000 people have been killed and 1.9 million people have been displaced by the fighting, according to the UN.
The government says only 10,000 have been killed in the conflict and blames the lack of security in Darfur on tribal conflict, minority armed forces and banditry.
Violence has ebbed from its peak in 2003-2004 but analysts say there is no end in sight to the conflict because of divisions among the rebels.