Issouf Sanogo / AFP - Getty Images

Nigerian soldiers arrive at the airport in Bamako on Thursday as part of the West African force meant to help French troops drive Islamists from their strongholds in northern Mali.

BAMAKO/SEGOU, Mali — The first West African regional forces arrived in Mali on Thursday to reinforce French and Malian troops battling to push back al Qaida-linked rebels after seven days of French air strikes.

A contingent of around 100 Togolese troops landed in Bamako and was due to be joined by Nigerian forces already en route. Nigerien and Chadian forces were massing in Niger, Mali's neighbor to the east.

The scrambling of the U.N.-mandated African mission, which previously had not been due for deployment until September, will be a boon for France, the former colonial power in Mali.

French troops, which had moved northwards from Bamako in an armored column on Tuesday, pinned down some Islamist fighters in the small town of Diabaly. But French forces held back from launching an all-out assault as the insurgents had taken refuge in the homes of civilians, residents said.

"The Islamists are still in Diabaly. They are very many of them. Every time they hear a plane overhead, they run into homes, traumatizing the people," said one woman who fled the town with her three children overnight.

Residents in the town of Konna, to the north of the central garrison town of Sevare, said Islamists had fled as Malian soldiers backed by French troops deployed.

"Life is difficult for the people of northern Mali and the international community has the duty to help these people," said Togolese Lieutenant Colonel Mawoute Bayassim Gnamkoulamba.

"That is why we think that it is necessary for us to protect Mali and we are proud today to fulfill that mission."

French forces, numbering some 1,400 soldiers, began ground operations on Wednesday against an Islamist coalition grouping al Qaida's North African wing AQIM and the home-grown Ansar Dine and MUJWA militants.

Averting creation of a 'terrorist state'
French President Francois Hollande ordered the intervention on the grounds that the Islamists who had taken over the poor West African country's north could turn it into a "terrorist state" which would radiate a threat beyond its borders.

Hollande has pledged they will stay until stability returns to Mali but, in the first apparent retaliatory attack, al Qaida-linked militants took dozens of foreigners hostage at a gas plant in Algeria, blaming Algerian cooperation with France.

Meantime, the United States agreed to a French request for airlift capacity to help troops and equipment to Mali, a limited expansion of American support in the battle against Islamist rebels there, U.S. officials said on Thursday.

One U.S. official said the Air Force could start cargo flights, likely using C-17 aircraft but possibly also larger C-5s, in as little as a day. But details have yet to be worked out and no timetable has been decided.

A total of 2,500 French troops are expected in Mali but Paris is keen to swiftly hand the mission over to West Africa's ECOWAS bloc, which in December secured a U.N. mandate for a 3,300-strong mission to help Mali recapture its north.

A rebel push into central Mali was last week halted by bombings by French aircraft and the deployment of ground troops.

A convoy of armored vehicles, fuel tankers and ambulances and around 200 soldiers from Mali's eastern neighbor Niger was positioned at that eastern border, witnesses said.

A Reuters witness at the scene said heavy weapons fire rang out as troops tested artillery.

Communications with residents in Islamist-controlled towns have become more difficult as some mobile phone towers have stopped working. Residents said rebel fighters are suspicious of anyone using phones, fearing they are passing information to the enemy.

"There are no longer any police stations. (The Islamists) have dispersed across the city, mixing in with the population," said Ibrahim Mamane, a resident from the town of Gao who reached the border with Niger.

"The population is ready and is waiting for the French forces with open arms. If they attack Gao, the people will fight the Islamists with their bare hands," he added.

Reuters journalists travelling north of Bamako saw residents welcoming French troops and, in places, French and Malian flags hung side by side.

Mali's recent troubles began with a coup in Bamako last March, ending a period of stable rule that saw a series of elections. In the confusion that followed, Islamist forces seized large swathes of the north and imposed a strict rule reminiscent of Afghanistan under the Taliban.

Military experts say France and its African allies must now capitalize on a week of hard-hitting air strikes by seizing the initiative on the ground to prevent the insurgents from withdrawing into the desert and reorganizing.

"The whole world clearly needs to unite and do much more than is presently being done to contain terrorism," Nigerian President Goodluck Jonathan said.