The dead include nine security personnel and 11 assailants, with many more injured, said the statement, which was signed by Col. Idrissa Traore, deputy director of communication for Mali's defense ministry.
He identified the attackers as "an armed gang linked to drug traffickers" - government code for Tuareg rebels.
Hours after the attack, the rebel Tuareg Alliance for Change of Northern Mali, known by its French acronym of ATNMC, posted a statement on its Web site claiming responsibility for the incident. Rebel spokesman Hama Ag Sid'Ahmed said in the statement 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," the rebel statement said.
Mali's President Amadou Toumani Toure called for calm. "No one can divide Mali," he said.
There had been a Tuareg rebellion in the 1990s, followed by years of peace. Mali signed a peace deal with a number of Tuareg groups last year to end the insurgency, which had reignited in 2006.
But one faction - led by Ibrahim Ag Bahanga, the leader of the ATNMC - refused to sign the deal, saying it did not do enough to help the Tuareg minority, whose nomadic culture sets them apart from Mali's southern ethnic groups. Bahanga's group has been blamed for numerous attacks on military installations and for kidnapping soldiers and government security officers.
In March, negotiators from Bahanga's group and the government started meeting in the Libyan capital of Tripoli. The latest deal promised renewed efforts to increase development in the impoverished north and increase government opportunities for members of the ethnic group.