Abdel Aziz "just obtained a ceasefire here in Kidal from representatives of the three armed groups he was meeting... Through this ceasefire, the groups undertake to stop fighting and stay where they are," the source told AFP by telephone from Kidal.
The source could not immediately provide any further details on the negotiations but said Abdel Aziz, the Mauritanian president, would leave "any time now".
Around 20 Malian soldiers have been killed and 30 wounded since Wednesday as Tuareg and Arab insurgents captured the flashpoint northern town of Kidal and the smaller settlement of Menaka, according to the defence ministry.