Mali's president called for a ceasefire in the restive north of the country and ordered three days of mourning as Tuareg separatists claimed they captured more than a key desert bastion after slaying several soldiers. Tuareg militants killed the soldiers during clashes in the rebel-held town of Kidal on Wednesday, a United Nations source told AFP, as a rebel leader said three armed groups had also taken other northern towns. After clashes during the day "the situation is calm tonight in Kidal", which is under the control of rebel groups, National Movement for the Liberation of Azawad (MNLA) spokesman Moussa Ag Assarid told AFP from Kidal. "We took several towns from where the army fled without a fight," he added, citing Anderamboukane, Menaka, Aguelhoc, Tessalit and Anefis. Mohamed Ag Rhissa, one of the MNLA leaders, told AFP by telephone his group had taken "control of the whole town of Kidal" and that "we have prisoners". The fighting shattered an uneasy calm, which had held since the MNLA took 32 civil servants hostage during a battle that left eight Malian soldiers and 28 rebels dead. "The noise of gunfire has stopped... There are prisoners and deaths among the Malian army's ranks," a source from the MINUSMA, the United Nations peacekeeping mission in Mali, told AFP, adding that the rebels appeared to have the upper hand. The fighting first broke out during a visit to Kidal on Saturday by Prime Minister Moussa Mara, whose government is backed by French soldiers who have helped dislodge rebels and armed Islamic extremists from the desert north. The government has said that the MNLA is being backed in Kidal by Islamist fighters from Al-Qaeda in the Islamic Maghreb (AQIM), the Movement for Oneness and Jihad in West Africa (MUJAO) and others. - 'We took control of the city' - President Ibrahim Boubacar Keita called for an "immediate ceasefire" in the fighting in Kidal that had left "several wounded and caused the loss of human life", the government said in a statement. Keita's plea was "in line with requests by the UN secretary general and (made) in the name of the international community", said the statement read on public ORTM television by government spokesman Mahamane Baby. "Our men are still on the ground fighting the joint forces of AQIM, MUJAO and other militants. That's all we can say at the moment," a Malian defence ministry source had said earlier. Alghabass Ag Intalla, secretary general of the High Council for the Unity of Azawad, said his group and the Arab Movement of Azawad (MAA) had also played a key role in the fighting. "This morning, we were the first to have been attacked by the Malian army. So we took up our responsibilities. We mobilised the MNLA and MAA and together we took control of the city," he said. The hostages were freed on Monday as 1,500 Malian troops poured into Kidal, sent to restore government control to the bastion of the Tuareg separatist movement, 1,500 kilometres (900 miles) northeast of the capital. Mali descended into crisis in January 2012, when the MNLA launched the latest in a string of Tuareg insurgencies in the north. A subsequent coup in Bamako led to chaos, and militants linked to Al-Qaeda overpowered the Tuareg to seize control of Mali's northern half. A French-led military operation launched in January 2013 ousted the extremists, but sporadic attacks have continued and the Tuareg's demand for autonomy has not been resolved. Tuareg separatists occupied the regional governor's office for nine months before handing it back in November last year as part of a June peace deal that paved the way for presidential elections. But the process deeply divided the MNLA, whose ultimate goal is the independence of Azawad, the minority Tuareg name for their homeland in northern Mali. Up until the agreement, the Tuareg group had refused to allow any government soldiers or civil servants into the desert town. - 'Sincere dialogue' - The UN Security Council in a statement Tuesday called for an end to violence across northern Mali. It also called for "sincere" peace talks and "reiterated that only a credible and inclusive negotiation process can bring long-term peace and stability throughout the country". MINUSMA sources said several hundred people had fled their homes in Kidal to the relative safety of nearby desert camps. With the UN peacekeeping mission soon up for renewal, Foreign Minister Abdoulaye Diop has requested "a much more robust mandate, under Chapter VII of the UN charter" -- which allows for the use of force. This would enable the soldiers to "deal with threats on the ground and disarmament of all armed groups, in particular the MNLA", he said. The French army announced on Wednesday it had sent 100 soldiers to Gao, the largest city in northern Mali, where 1,000 of its troops are already stationed.