BAKAKO - Mali's army has launched a counter-offensive to retake the key central town of Konna seized by Islamist rebels on Thursday, military sources and local residents said on Friday.

"The army has launched an offensive on Konna. Helicopters have bombarded rebel positions. The operation will continue," a senior military source in Bamako told Reuters.

Residents in the nearby garrison town of Sevare, some 60 km to the south, reported the arrival of military helicopters and army reinforcements, which took part in the counterattack starting late on Thursday. Several witnesses also said foreign soldiers had arrived at the town's airport.