Mali\'s interim president Dioncounda Traore has formally asked west African forces to intervene to take back northern Mali from Islamist rebels, a senior French official said here Tuesday. \"President Traore formally sent a request to the Economic Community of West African States (ECOWAS) to provide a military contribution to stabilise the country and especially reconquer the north,\" said France\'s special representative for the Sahel region, Jean Felix-Paganon. \"This is an important development and we are discussing the possible developments\" with Burkina Faso\'s President Blaise Compaore, ECOWAS\' chief mediator, Felix-Paganon added. ECOWAS has said it is prepared to send a 3,300-strong force into Mali, but hopes to receive a UN mandate for the deployment which would also require an official request from the Malian transitional authorities. So far the interim government has been reluctant to allow in foreign troops but the changing situation on the ground could alter opinions. Once one of the region\'s most stable democracies, Mali has crumbled into turmoil since democratically elected president Amadou Toumani Toure was overthrown by the military in March. The ensuing political chaos allowed Al-Qaeda-linked Islamist rebels to seize control of the vast desert north, an area larger than France or Texas, where they have enforced strict sharia law. So far, interim authorities have proved unable to stem the crisis.