BAMAKO, Mali (AP) — France launched airstrikes Friday to help the government of Mali defeat al-Qaida-linked militants who captured more ground this week, dramatically raising the stakes in the battle for this vast desert nation.

French President Francois Hollande said the ‘‘terrorist groups, drug traffickers and extremists’’ in northern Mali ‘‘show a brutality that threatens us all.’’ He vowed that the operation would last ‘‘as long as necessary.’’

France said it was taking the action in Mali at the request of President Dioncounda Traore, who declared a state of emergency because of the militants’ advance.

The arrival of the French troops in their former colony came a day after the Islamists moved the closest yet toward territory still under government control and fought the Malian military for the first time in months, seizing the strategic city of Konna.

Sanda Abou Moahmed, a spokesman for the Ansar Dine group, condemned Mali’s president for seeking military help from its former colonizer.

‘‘While Dioncounda Traore asked for help from France, we ask for guidance from Allah and from other Muslims in our sub-region because this war has become a war against the crusaders,’’ he said by telephone from Timbuktu.

For the past nine months, the Islamic militants have controlled a large swath of northern Mali, a lawless desert region where kidnapping has flourished.

‘‘French armed forces supported Malian units this afternoon to fight against terrorist elements,’’ Hollande said in Paris.

He did not give any details of the operation, other than to say that it was aimed in part at protecting the 6,000 French citizens in Mali, where seven of them already are being held captive.

French Foreign Minister Laurent Fabius, when asked whether France had launched airstrikes, said, ‘‘To the question of whether there was an air intervention, the response is yes.’’ He refused to give any other details for security reasons.

France is operating helicopter gunships in Mali, two diplomats told The Associated Press. They spoke on condition of anonymity because they were not authorized to discuss the operation publicly. French special forces, who have been operating in the region recently, are also believed to be taking part in the military operation, one diplomat said.

U.N. Secretary-General Ban Ki-moon told the AP that Senegal and Nigeria also responded to an appeal from Mali’s president for help to counter the militants.

Residents in central Mali said they had seen Western military personnel arriving in the area, with planes landing at a nearby airport throughout the night.

Col. Abdrahmane Baby, a military operations adviser for the foreign affairs ministry, confirmed in the Malian capital of Bamako that French forces had arrived in the country but gave no details.

‘‘They are here to assist the Malian army,’’ he told reporters.

Traore went on national television Friday night to declare the state of emergency, saying it would remain in effect for 10 days and could be renewed.

‘‘The situation on the front is over all under control,’’ he said.

Traore called on mining companies and nongovernment organizations to turn their trucks over to Malian military, raising questions about the army’s ability.

State Department spokeswoman Victoria Nuland said the U.S. was ‘‘deeply concerned’’ by events in Mali, and that Washington was closely consulting with Paris. She said neither France nor Mali has asked for U.S. military assistance.

France has led a diplomatic push for international action in northern Mali but efforts to get an African-led force together, or to train the weak Malian army, have dragged.

The French quickly mobilized after the Islamists seized the city of Konna on Thursday, pushing closer to the army’s major base in central Mali. Late Friday, Malian Lt. Col. Diarran Kone said the government had not been able to recapture the town.

The United Nations Security Council has condemned the capture of Konna and urged U.N. member states to assist Mali ‘‘in order to reduce the threat posed by terrorist organizations and associated groups.’’

Late last year, the 15 nations in West Africa, including Mali, agreed on a proposal for the military to take back the north, and sought backing from the U.N.

The Security Council authorized the intervention but imposed certain conditions. Those include the training of Mali’s military, which has been accused of serious human rights abuses since a military coup last year sent the nation into disarray.