Dioncounda Traore has been sworn in as Mali's interim president, marking a return to civilian rule following last month's coup in the West African state.The government of the former parliamentary speaker now has 40 days to organise elections.Correspondents say this deadline is unlikely to be met, however, with much of the vast northern region in the hands of separatist rebels.The role of coup leader Capt Amadou Sanogo also remains unclear.Mr Traore was sworn in by Supreme Court President Nouhoum Tapily at a brief ceremony in the capital, Bamako.West African states lifted sanctions against Mali after Capt Sanogo agreed to step aside.Before the deal, agreed on Friday, he had formally asked for the help of regional bloc Ecowas in defeating Tuareg separatists and their Islamist allies who had captured key northern towns.However, he has since said he needs only equipment and logistical support - and rejected the intervention of a 3,000-strong foreign force.Nevertheless, Ecowas is still mulling the possibility of sending in regional troops, and foreign ministers are meeting on Thursday in Ivory Coast's main city, Abidjan, for discussions.'Not charismatic'Correspondents say Mr Traore, 70, has long harboured presidential ambitions - but he had hoped to come to power through the ballot box by contesting elections originally scheduled for later this month.The former mathematician heads up Mali's largest political party, the Alliance for Democracy in Mali, and was an ally of the deposed President Amadou Toumani Toure, who formally resigned on Sunday.Known as ATT, the former president had been due to step down this month after two terms in office - and people had become increasingly frustrated with his government for doing little to tackle corruption and the growing insecurity and eventual rebellion in the north.As a consequence, many Malians are wary of Mr Traore, Bamako-based journalist Martin Vogl told the BBC's Network Africa programme.Mr Traore is not regarded as charismatic nor seen by many people as a natural leader, he says.Correspondents say that while Mr Traore's inauguration may bring hope, lasting peace in the north will not be achieved until the end of the political uncertainty in Bamako.Following the Ecowas deal, Capt Sanogo told the BBC on the subject of transferring power: "The agreement is clear. [Traore] will be here for 40 days and after 40 days, my committee and Ecowas will sit together and fix transition organs."Asked if that meant he would be back in power after that time, he replied: "I didn't say that. I don't know."Human rights group Amnesty International has warned of a major humanitarian disaster in the wake of the fighting in the north.The Tuaregs, who inhabit the Sahara Desert in Mali and several neighbouring countries, have fought several rebellions over the years, claiming they have been ignored by Bamako.