Gunmen ambushed a United Nations peacekeeping team on Saturday in Sudan's western region of Darfur, killing seven and wounding another 17 in the deadliest ever single attack on the international force in the country.

The assault included sustained heavy fire from machine guns and possibly rocket-propelled grenades, targeting the force some 15 miles west of the town of Khor Abeche, according to UN forces spokesman Chris Cycmanick. Reinforcements later arrived to rescue the wounded, including two female police advisers, the force said in a statement.

No group has claimed responsibility for the assault. Cycmanick declined to give the nationalities of those killed and wounded in the attack.

Peacekeepers have been targeted by assailants in the past in the region since the international force began its work there in 2008. In the last attack, gunmen shot dead a Nigerian peacekeeper in April in East Darfur state.

The joint African Union-UN peacekeeping force, dubbed Unamid, was established to protect civilians in Darfur, but also contributes to security for those providing humanitarian aid, verifying agreements, political reconciliation efforts and promoting human rights.

It has about 16,500 troops and military observers and over 5,000 international police. More than 300,000 people have been killed in the Darfur conflict since rebels took up arms against the Sudanese government nearly 10 years ago, accusing it of discrimination and neglect.

"The mission condemns in the strongest possible terms those responsible for this heinous attack on our peacekeepers," said Mohamed Ibn Chambas, a joint special representative of the force. "The perpetrators should be on notice that they will be pursued for this crime and gross violation of international humanitarian law."