Troops in Mali's capital, Bamako, mutinied on Wednesday, and gunfire could be heard throughout the city. The country's state-run radio and television broadcasts have gone off the air, news reports said.
Armored vehicles have sealed off the presidential palace, the BBC reported. The unrest comes less than a month before Mali is to hold presidential elections.
The government of President Amadou Toumani Toure has been struggling with an advancing Tuareg rebellion in the north, and there has been growing discontent in the Malian military. Soldiers have complained of a lack of weapons.
Aljazeera reports that Mali's latest upsurge in fighting was triggered by some 2,000-3,000 Tuareg combatants returning from Libya where they had served in former leader Muammar Gaddafi's battalions.