At least one United Nations peacekeeper has died in a rocket explosion at a joint UN-French owned military base in Kidal, north Mali.

"One (U.N.) soldier was killed in the attack," Olivier Salgado, a spokesman for the UN mission told Reuters. No details were given on the nationality of the peacekeeper so far.

Mali's prime minister Moussa Mara said Islamist militants had been given an opportunity to return to the north of the country after France decided to spread their troops across the whole of the region. He urged French and UN forces to continue guarding the area to stop the resurgence of Isis.

This latest killing is a continuation of reprisals against UN personnel. On Friday, nine UN peacekeepers from Niger were killed when gunmen travelling on motorbikes ambushed them. This is the worst attack on them so far in Mali.

The attack highlighted a rise in attacks on foreign troops based in Mali's northern desert region – particularly since Paris turned its Mali operation into a counter-militancy force this year after driving out Islamists from northern Mali in early 2013.

"The French forces are less concentrated and spread out across the Sahel-Sahara and so it's appeared like an opportunity for the groups to come and set up," Moussa Mara told Reuters.

The West African country is in disarray as Malian troops have abandoned many positions in the north earlier this year after clashes with the rebels. In the power vacuum, control has been seized by various groups including Islamists as well as drugs and weapons smugglers.

Mara called on the UN peacekeeping mission to send more of its 12,000 men to the north, and to use the helicopters and special forces to hunt down the Islamists, who, with separatists, took advantage of the disarray created by a coup in 2012 to seize the northern regions.

One of the challenges for the UN force in Mali has been the size of the former French colony, which has a population of 16 million people.

Under the terms of a proposed deal in June 2013 to end the Malian uprising, the separatist groups agreed to sever all ties with the Islamist rebels in the run-up to talks.

"Today, every time we have armed clashes in the north, we think they are fighting more to secure drug trafficking routes than fighting terrorists," the Malian PM said. "The armed groups must stop this."