The African Union (AU) has backed a plan to send troops into Mali to clear the north of Islamist extremists. It endorsed the decision by West Africa's regional bloc Ecowas on Sunday to send 3,300 troops to help Mali's government retake the region. The plans will now go before the UN Security Council for approval before the end of the year. Islamist groups and Tuareg rebels took control of the north after Mali's president was overthrown in March. The UN has warned that the Islamist militias are imposing a harsh version of Sharia law on the areas they control and that forced marriage, forced prostitution, and rape are becoming widespread. 'Dismantle terror networks' The Ecowas plan covers a six-month period, with a preparatory phase for training and the establishment of bases in Mali's south, followed by combat operations in the north, Malian army sources told Reuters news agency. The soldiers would be provided mainly by Nigeria, Niger and Burkina Faso. After endorsing the plan, the AU's Peace and Security Commissioner, Ramtane Lamamra, said other African countries could provide troops and logistical support. Map "This deployment aims to respond to the request by the Malian authorities to regain the occupied regions in the north of the country, dismantle the terrorist and criminal networks and restore effectively the authority of the state over the entire national territory," he told reporters in the Ethiopian capital, Addis Ababa, where the AU is based. The Ecowas plan is the result of a 45-day deadline the UN gave African leaders on 12 October to draw up a plan for military intervention to retake the north. West African battalions will need logistical and intelligence support from outside the region, as well as air power, to engage in a military operation that could last months, the BBC's West Africa correspondent Thomas Fessy reports. The European Union is to discuss sending hundreds of instructors to train the Malian army, which was brought to its knees by rebel groups, our correspondent adds. French President Francois Hollande reiterated on Tuesday that France would provide "logistical support and training" for any mission to Mali, but would not send in soldiers. Mali's neighbour Algeria has expressed concern about the use of military intervention, saying it would prefer a negotiated solution. Security experts and observers say it may still take months before a force is ready to retake the north, which should give more time for negotiations to continue with at least one of the main armed groups already engaged in talks, our correspondent notes. President Amadou Toumani Toure was overthrown in March by a junta of disaffected soldiers who claimed his government had not dealt effectively with a Tuareg rebellion that had started in January. Islamist groups - who have since fallen out with their Tuareg allies - took advantage of the ensuing chaos and seized all the region's major towns, including the historic city of Timbuktu.