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.
A number of French aircraft, including helicopters, had landed overnight at Kidal airport.
Islamist militants were reported to have already left the town and it was unclear who was in control.
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.
‘Eradicate terrorism’
French army spokesman Col Thierry Burkhard confirmed that “French elements were deployed overnight in Kidal”.
One regional security source told Agence France-Presse that French aircraft had landed at Kidal and that “protection helicopters are in the sky”.
Kidal, 1,500km (930 miles) north-east of the capital Bamako, was until recently under the control of the Ansar Dine Islamist group.
However, the Islamic Movement of Azawad (IMA), which recently split from Ansar Dine, said it was now in charge in Kidal, although the Tuareg group – the National Movement for the Liberation of Azawad – also claims control.
An MNLA spokesman told the BBC its fighters had entered the city on Saturday and there were no Islamist militants there.
A spokesman for the IMA confirmed the French arrival and said that its leader was now in talks with them.
The IMA recently said it rejected “extremism and terrorism” and wanted a peaceful solution.
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”.
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.
Islamist extremists took advantage of a military coup in March last year to control a number of cities in the north and impose sharia law.
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.