The US military has begun airlifting French soldiers and equipment to Mali to support their operation against Islamist militants. Five US flights had already landed in the capital, Bamako, with more planned in the coming days, a spokesman said. France began its intervention nearly two weeks ago with the aim of halting the militants' advance south. It plans to hand command of the operation to a West African force which has some 1,000 soldiers on the ground. An estimated 2,000 French troops are currently in Mali, with 500 more expected. Desert fighters C17 transport planes had begun flights from a French base in Istres, in southern France, the US military's Africa Command said on Tuesday. Pentagon spokesman George Little told Reuters news agency five sorties had been flown so far. "The priority is to move heavy, bulky things" such as armoured vehicles, French military spokesman Thierry Burkhard told the AFP news agency. The UK, Belgium, Canada, Denmark and Italy are also providing transport planes for the French mission. Initially, the US said it would provide communications help for the operation. On Monday, French and Malian troops seized two key towns - Diabaly and Douentza - from the militants, after they had fled. Col Burkhard said selected French air strikes had continued in the north, where Islamist militants had gained control last year. Last month, the UN approved plans to send some 3,000 West African troops to Mali in September to recapture the vast desert region. But, following France's intervention, the regional force, which will be under Nigeria's command, has begun an urgent deployment. Chad, which is not part of the regional body Ecowas, is also sending 2,000 soldiers to work in co-ordination with French troops. Analysts say their foot soldiers are experienced desert fighters and are likely to face combat, with the bulk of the Ecowas troops providing more of a policing role. Mali's army chief General Ibrahima Dahirou Dembele told AFP that Chadian troops would join some 500 Nigeri troops in western Niger with the aim of crossing the border and heading towards the town of Gao, in north-eastern Mali. Meanwhile, UN Secretary General Ban Ki-moon has praised France's intervention, saying dialogue with the militants was not possible "at this time", AP reports. Islamist groups and secular Tuareg rebels took advantage of chaos following a military coup to seize northern Mali in April 2012. But the Islamists soon took control of the region's major towns, including Gao and Timbuktu, sidelining the Tuaregs.