French forces say they have entered Kidal in the north of Mali, the last major town they have yet to secure in their drive against Islamist militants.French forces now control Kidal airport after a number of aircraft, including helicopters, landed there overnight.Islamist militants were reported to have already left the town and it was unclear who was in charge.French and Malian forces have been sweeping north, earlier taking Gao and Timbuktu with almost no resistance.France - the former colonial power in Mali - launched a military operation this month after Islamist militants appeared to be threatening the south.French army spokesman Col Thierry Burkhard confirmed that "French elements were deployed overnight in Kidal".Haminy Maiga, the interim president of the Kidal regional assembly, told the Associated Press news agency: "The French arrived at 9:30pm [Tuesday] aboard four planes. Afterwards they took the airport and then entered the town and there was no combat."The French are patrolling the town and two helicopters are patrolling overhead," he said.'Eradicate terrorism'Kidal, 1,500km (930 miles) north-east of the capital Bamako, was until recently under the control of the Ansar Dine Islamist group, which has strong ties to al-Qaeda in the Islamic Maghreb (AQIM).The Islamist militants had taken advantage of a military coup in March last year to impose Sharia in a number of cities in the north.However, the Islamic Movement of Azawad (IMA), which recently split from Ansar Dine, says it is now in charge in Kidal.The IMA has said it rejects "extremism and terrorism" and wants a peaceful solution.An IMA spokesman confirmed the French arrival in Kidal and said that its leader was in talks with them.However, another rebel group, the secular National Movement for the Liberation of Azawad (MNLA), is also influential in the area. It is ethnically driven, fighting mostly for the rights of Mali's minority Tuareg community.An MNLA spokesman told the BBC its fighters had entered Kidal on Saturday and found no Islamist militants there.The MNLA has also said it is prepared to work with the French "to eradicate terrorist groups" in the north but that it would not allow the return of the Malian army, which it accused of "crimes against the civilian population".Some reports say Ansar Dine leader, Iyad Ag Ghaly, and Abou Zeid of AQIM have now moved to the mountainous region north of Kidal.The BBC's Thomas Fessy, in Timbuktu, says that taking Kidal will mark the end of the first phase of the French military intervention, but that there will remain the difficult task of chasing the fighters down across the vast desert.The French arrival at Kidal came only 24 hours after securing Timbuktu with Malian forces.The troops had to secure the streets after hundreds of people looted shops they said had belonged to militant sympathisers.France has been pushing for the swift deployment of an African Union-backed force, the International Support Mission to Mali (Afisma), to take control of Malian towns.On Tuesday, international donors meeting in Ethiopia pledged $455.53m (£289m) for Afisma and for other projects.African leaders say the overall budget could be around $950m.France's Foreign Minister Laurent Fabius told the meeting impressive progress had been made but that this did not mean the danger was over.Mr Fabius also said credible elections in Mali would be vital to achieving sustainable peace in the country.Mali's interim President Dioncounda Traore said on Tuesday that he wanted to hold "transparent and credible" elections by 31 July.