Renegade Malian soldiers went on state television on Thursday to declare they had seized power in a coup after the government's failure to quell a nomad-led rebellion in the north.

The soldiers of the newly formed National Committee for the Restoration of Democracy and State (CNRDR) read out a brief statement after heavy weapons fire rang out around the presidential palace in the capital Bamako throughout the night.

"The CNRDR has decided to assume its responsibilities by putting an end to the incompetent regime of Amadou Toumani Toure," said Amadou Konare, spokesman for the National Committee for the Restoration of Democracy and State (CNRDR).

"We promise to hand power back to a democratically elected president as soon as the country is reunified and its integrity is no longer threatened," said Konare flanked by about two dozen soldiers. A subsequent statement declared an immediate curfew 'until further notice'.

The statements made no reference to the whereabouts of Toure, who for the past decade has presided over one of the more stable governments in West Africa and was due in any case to step down after elections scheduled for late next month.

However the gold- and cotton-producing nation has struggled to contain a northern rebellion launched late last year by local Tuareg nomads joined by heavily armed fellow Tuaregs returning from Libya after fighting for ousted leader Muammar Gaddafi.

The rebellion, in which dozens have been killed and nearly 200,000 civilians have fled their homes, has added a new layer of insecurity to a region where al Qaeda allies have carried out a spate of kidnappings of Westerners and other crimes.

U.N. Secretary-General Ban Ki-moon called for calm and for grievances to be settled democratically in a statement hours before the soldiers said they had seized power.

Jean Ping, head of the commission of the African Union continental grouping, said he was "deeply concerned by the reprehensible acts currently being perpetrated by some elements of the Malian army".

WIDER FRUSTRATIONS
Sporadic heavy weapons and tracer fire rang out in Bamako through the night and the mutineers, who say they lack arms and resources to face the separatist insurgency in the Sahara, temporarily forced the state broadcaster off air.

"We now know it is a coup d'etat that they are attempting," one defence ministry official said, asking not to be named.

The official said Toure was in a secure location but gave no more details. There was no word from Mali's presidency. Statements posted by its official Twitter handle on Wednesday had denied there was a coup attempt.

Anger has grown in the army at the handling of the rebellion that has exposed Bamako's lack of control over the northern half of a country twice the size of France.

In a sign of the breadth of the army mutiny, two military sources in the northern town of Gao confirmed the arrests of several senior officers in the town, a regional operations centre for the military.

Soldiers have for weeks appealed to the government for better weapons to fight the rebels, who are bolstered by fighters who had fought in Libya's civil war last year.

Bamako was briefly paralyzed last month as hundreds of Malians put up street barricades and burned tires in the streets to protest at the government's handling of the rebellion.

A military source said a trigger for Wednesday's events was a visit by the defense minister to a barracks in the town of Kati about 20 km (13 miles) north of Bamako.

"The minister went to speak to troops but the talks went badly and people were complaining about the handling of the crisis in the north," the source said.

A defense ministry official who was at the meeting said a soldier accused the defense minister of betraying them by not giving them means to fight the rebels. Soldiers then began throwing rocks at the minister before taking weapons from the armory and shooting in the air.

Tuareg fighters seeking to carve out a desert homeland in Mali's north have made advances in recent weeks, including the seizure this month of the key garrison town of Tessalit by the Algerian border.