In this picture dated Thursday, Jan. 17, 2013 and released by the French Army Communications Audiovisual office (ECPAD) Nigerian troops for the African-led international support mission to Mali exit a military plane at Bamako airport, Mali. France remains alone as the only foreign power with boots on the ground, though on Thursday, a contingent of Togolese and Nigeria soldiers arrived at the airport. A Malian soldier stands guard in front of a strategic bridge in Markala, approximately 40 km outside Segou on the road to Diabaly, in central Mali, Thursday, Jan. 17, 2013. Fighting raged in one Mali town, airstrikes hit another and army troops raced to protect a third, on Thursday, the seventh day of the French-led military intervention to wrest back Mali's north from al Qaida-linked groups. French troops arrive at Bamako's airport Thursday Jan. 17, 2013. Over 600 soldiers arrived Thursday. Fighting raged in one Mali town, airstrikes hit another and army troops raced to protect a third, on the seventh day of the French-led military intervention to wrest back Mali's north from al Qaida-linked groups. In this picture released by the French Army Communication Audiovisual office (ECPAD) French military vehicles drive to the north of Mali, at an undisclosed location, Wednesday, Jan. 16, 2013. BAMAKO, Mali (AP) - French troops encircled a key Malian town on Friday to stop radical Islamists from striking closer to the capital, a French official said. The move to surround Diabaly came as French and Malian authorities said they had retaken Konna, the central city whose capture prompted the French military intervention last week. The United Nations warned that some 700,000 civilians could be displaced by the fighting in Mali, where the French-led international force is fighting to oust the rebels from power in the north. The French forces moved around Diabaly to cut off supplies to the Islamist extremists, who have held the town since Monday, said a French official who spoke on condition of anonymity to be able to discuss sensitive security matters. The Malian military chased the Islamists from Konna and are now holding the town, a Malian military official, who insisted on anonymity because he was not authorized to speak to journalists, said Friday. Telephone lines were cut off in the town, making it difficult to independently verify the claim though the French official also confirmed the rebels no longer hold Konna. Doctors Without Borders has been trying to get to Konna since Monday but all roads leading to the community in central Mali have been closed by the Malian military, said Malik Allaouna, director of operations for the group known as MSF for its initials in French. "Despite our repeated requests, we are still being refused access to the Konna region," he said. It is essential to allow the delivery of neutral and impartial medical and humanitarian aid in the areas affected by the conflict. In Geneva, United Nations refugee agency spokeswoman Melissa Fleming said that the number of displaced Malians is expected to increase dramatically in the coming months. Those who have fled "mentioned that large amounts of money are being offered to civilians to fight against the Malian army and its supporters," she said. Meanwhile, authorities in the town of Niono said that a key road leading to Segou was being closed to traffic Friday between 6 p.m. and 8 a.m. Segou is one of the largest towns in Mali and the administrative capital of its central region. The road closure is an attempt to keep Islamists from entering towns further south, officials said. The prefect, or district administrator, of Niono Seydou Traore said "neither cars, nor motorcycles, nor people on foot will be able to travel, as a security measure." France has encountered fierce resistance from the extremist groups, whose tentacles extend not only over a territory the size of Afghanistan in Mali, but also another 600 miles (1,000 kilometers) to the northeast in Algeria, where fighters stormed a BP-operated plant and took dozens of foreigners hostages, including Americans. They demanded the immediate end of the hostilities in Mali, with one commander, Oumar Ould Hamaha, saying that they are now "globalizing the conflict" in revenge for the military assault on Malian soil. On Thursday, France increased its troop strength in Mali to 1,400, said French Defense Minister Jean-Yves Le Drian. West African neighbors also have begun sending troops to aid the French-led mission, with some Togolese and Nigerian forces arriving Thursday. Nigeria has offered another 900 soldiers, while Chad has said it will send 2,000 to aid the mission. A former French colony, Mali once enjoyed a reputation as one of West Africa's most stable democracies with the majority of its 15.8 million people practicing a moderate form of Islam. Associated Press writers Angela Charlton in Paris; Rukmini Callimachi in Bamako, Mali; and John Heilprin in Geneva contributed to this report.