BAMAKO (AFP) - Two UN peacekeepers from Guinea and a civilian contractor were killed Saturday in a rocket attack on a UN base in northeastern Mali claimed by the militant Ansar Dine group, a week after a deadly siege at a Bamako hotel shocked the country.

The United Nations peacekeeping mission in Mali (Minusma) said in a statement that the pre-dawn attack on the camp in Kidal also left some 20 people injured, four of them seriously.

"Our camp in Kidal was attacked early this morning by terrorists using rockets," a Minusma official told AFP.

Two Guinean peacekeepers and a contractor from Burkina Faso died in the attack, the UN said.

"The terrorists fired shots and then fled," another UN source said.

The UN Security Council urged the Malian government to "swiftly investigate this attack and bring the perpetrators to justice".

"The members of the Security Council underlined that attacks targeting peacekeepers may constitute war crimes under international law," it added.

A senior Ansar Dine (Defenders of the Faith) figure, Hamadou Ag Khallini, told AFP that the attack was "in response to the violation of our lands by the enemies of Islam."

"We claim the attack in the name of all the mujahedeen," he said.

The Ansar Dine group is allied to Al-Qaeda in the Islamic Maghreb (AQIM) and the Macina Liberation Front, the latter of which claimed responsibility for the Nov 20 attack on the luxury Radisson Blu hotel in Mali's capital during which 20 people died, including 14 foreigners.

In a siege that last around nine hours, armed men held around 170 guests and staff hostage before Malian, French and US forces stormed the hotel to free the captives, killing two assailants.

Two separate militant groups claimed responsibility for that assault: the Al-Murabitoun group, an Al-Qaeda affiliate led by notorious one-eyed Algerian militant Mokhtar Belmokhtar, and the Macina Liberation Front from central Mali.

Four days later, a UN employee was killed in an attack on a peacekeeping convoy near the historic desert town of Timbuktu.

Minusma chief Mongi Hamdi said in a statement Saturday that the attacks "would not dent the determination of the UN to support the Malian people and the peace process, including assisting in the implementation of the Agreement on Peace and Reconciliation in Mali".

Mali has been plagued by unrest since the north of the vast west African state fell under the control of Tuareg rebels and extremist groups linked to Al-Qaeda in 2012.

The Islamists soon sidelined the Tuareg to take sole control of Timbuktu, Kidal and other northern towns but lost most of the ground they had captured in a French-led military intervention in January 2013.

Nearly three years later, large swathes of Mali still remain lawless despite a June peace deal between the government and Tuareg rebels seen as crucial to ending decades of instability in the north that left it vulnerable to extremism.

Some splinter groups had opposed the agreement, including the Tuareg head of the Ansar Dine group, Iyad Ag Ghaly, who called in an October recording for further attacks, including against France.

France has more than 1,000 troops in Mali, a former colony and a key battleground of its Barkhane counter-terror mission spanning five countries in Africa's restive Sahel region.

The UN mission in Mali comprises around 10,200 peacekeepers, who have come under frequent attack.

With more than 50 fatalities so far, Minusma has been one of the deadliest UN missions in recent years.

This year has seen the violence spread to the centre and south of Mali, which had previously been largely spared by the extremists.