Tuareg rebels are demanding greater autonomy
At least 20 people have been killed and several taken hostage in an attack by Tuareg rebels on a military base in northern Mali, officials have said.
The Malian defence ministry said the raid occurred shortly before dawn in the town of Nampala, 500km (310 miles) north-east of the capital, Bamako.
The dead included nine security troops and 11 attackers, it added. The rebels say they killed more than 20 soldiers.
It was the first major clash since a peace deal was signed in July.
Last week, Malian President Amadou Toumani Toure called on the rebels to lay down their arms, saying that "those who want war can go elsewhere".
"I have been trained to make war, but I prefer peace," the former army general said during a visit to northern Mali last Sunday.
But the BBC's West Africa correspondent Will Ross says the attack shows that yet another attempt to make peace in Mali has failed.
Military sources said a rebel column of more than 20 vehicles had raided the base in Nampala early on Saturday and left behind a scene of "carnage". Several hostages were also taken, the sources said.
The defence ministry identified the attackers as "an armed gang linked to drug traffickers", a description it often uses to describe Tuareg rebel groups.
The North Mali Tuareg Alliance for Change (ATNMC), which did not sign the peace deal in July, has claimed responsibility for the attack in a statement on its website.
A source close to the group's leader, Ibrahim Ag Bahanga, said its fighters had gained the upper hand in the attack" and killed "more than 20" soldiers.
"We regret that, but it was them or us. We have wounded on our side," the unnamed source told the AFP news agency.
An ATNMC spokesman, Hama Ag Sid'Ahmed, said the attack was intended to force the government into dialogue.
"So that we can move beyond the current impasse which has lasted for the past three years, we want the Malian authorities... [to reinitiate] a real dialogue," he said in a statement.
President Toure called for calm and national unity following the incident.
"No-one can divide Mali," he said.
The Tuaregs, a historically nomadic people living in the Sahara and Sahel regions of North Africa, want more resources to be spent in their homeland and greater autonomy.
Tuareg militant groups in Mali and Niger have been engaged in sporadic armed struggles seeking these goals for several decades.