The European Union on Thursday condemned renewed fighting in Mali's desert town of Kidal, a day after Tuareg rebels claimed control, and demanded the "immediate implementation" of a truce.
The army and Tuareg separatists of the National Movement for the Liberation of Azawad (MNLA) had breached a ceasefire signed under a "preliminary peace accord of June 18, 2013", the EU's diplomatic service said in a statement.
"The immediate implementation of a ceasefire is an indispensable step in light of the reopening of negotiations in the framework of a process of dialogue and reconciliation as planned," the statement said.
Tuareg fighters on Wednesday killed several Malian soldiers in Kidal, which lies deep in the Sahara more than 1,500 kilometres (930 miles) from the capital Bamako, a United Nations source said.
Mohamed Ag Rhissa, one of the MNLA leaders, told AFP by telephone on Wednesday that his armed supporters had taken "control of the whole town of Kidal", which has at times been a bastion of the traditionally nomadic tribes of the desert.
"We have prisoners," he added.
The fresh fighting shattered an uneasy calm that had held since the MNLA took 32 civil servants hostage during a May 17 battle that left eight Malian soldiers and 28 rebels dead. The UN mission in Mali, MINUSMA, negotiated the release of the captives.
The EU declared itself ready to help moderate "talks, with respect for the unity, territorial integrity and national sovereignty of Mali," according to the spokesman.
President Ibrahim Boubacar Keita has already called for an "immediate ceasefire" in Kidal, in a statement read on public television, which said the plea was "in line with requests by the UN secretary general and (made) in the name of the international community".
The Tuareg rebels have claimed to control several other small northern towns. The government has said its troops in the north are battling Islamic extremist fighters currently backing the MNLA.
France last year sent military forces to its vast and poor former west African colony, and succeeded in driving Al-Qaeda-linked extremists and Tuareg forces out of northern towns, to melt away into the desert.
On Tuesday, in light of the latest fighting, French defence sources said that Paris had decided to postpone a planned drawdown and redeployment of its forces in Mali.