French warplanes have bombed rebel bases and depots in remote parts of northern Mali to try to cut off supply routes, France's foreign minister says.Laurent Fabius told France Inter radio that the rebels would not be able to stay long without fresh supplies.Thirty jets struck on Sunday around Tessalit amid fears the rebels could re-group in the mountainous region.In Paris, US Vice-President Joe Biden backed plans for an African-led force and eventual UN operation in Mali.Speaking alongside French President Francois Hollande, who visited Mali at the weekend, Mr Biden said they had agreed that African troops should take over from French forces "as quickly as reasonably possible", before the UN assumes overall command.Efforts must then be made "as quickly as is prudent [to] transition that mission to the United Nations," Mr Biden said.Mr Hollande said the French-led mission would continue, with the aim of restoring Mali's "territorial integrity" before peacekeeping operations began. Kidal talksSpeaking before his president's appearance at the Elysee Palance, Mr Fabius said that Sunday's air strikes had been aimed at "destroying the bases and fuel depots" of the rebels."If you look at the map, they have taken refuge in the north and in the north-east," Mr Fabius said."But they can stay there for long only if they have ways to get supplies. So, in a very efficient manner, the army is stopping that."Mr Fabius would not say whether the air strikes were aimed at preparing for a new ground assault, but said transition to African forces - and withdrawal from Timbuktu - "could happen very fast".The French launched their intervention in Mali on 11 January as Islamist militants moved south and threatened the capital, Bamako.Since then, the militants have been driven from population centres in the north and east.Kidal remains the only major town not in the control of French and Malian forces.French troops are at the airport in Kidal, but rebels from a Tuareg group who want their own homeland in northern Mali - the MNLA - still control the town itself.Malian Interim President Dioncounda Traore has offered to hold talks with the MNLA in order to help secure Kidal.Tessalit is about 200km (125 miles) north of Kidal and is a gateway to the Adrar des Ifoghas mountains, where rebels are believed to have sought refuge after being forced from the main population centres.It is thought the mountainous areas could provide perfect hiding places for the militants.