The spokesman said the peacekeeper's body was found on Wednesday evening near an outdoor market in the North Darfur capital of El Fasher, and an investigation was under way.

"We are peacekeepers. We are not here to participate in the conflict, so it is a shock to receive news of what happened," said the spokesman, Noureddine Mezni, who identified the officer as a police adviser with the joint U.N./African Union Mission in Darfur (UNAMID).

Mezni said the Ugandan was the first peacekeeper to be killed in Darfur since UNAMID troops took over from a beleaguered African Union force at the beginning of the year. Others have died of natural causes.

None of the officer's belongings were taken from the car, Mezni said, adding that it was too early to ascribe blame or motive for the attack. Sudan's state news agency SUNA described the killing as a "criminal" act.

The United Nations has warned that the Darfur peacekeeping force remains seriously undermanned -- with only 9,000 out of a promised 26,000-strong force on the ground -- and poorly equipped. The force was sent to keep the peace in a remote region about the size of France.

Law and order has collapsed in Darfur where U.N. officials say five years of conflict have killed up to 300,000 and driven 2.5 million from their homes. Khartoum puts the death count at 10,000 and accuses Western media of exaggerating the conflict.