BAMAKO, Mali — France claimed new successes in its campaign to oust Islamist extremists from northern Mali on Sunday, bombarding the major city of Gao with airstrikes targeting the airport and training camps used by the Al Qaeda-linked rebel group controlling the city.
France’s foreign minister also said the three-day-old intervention is gaining international support, with communications and transport help from the United States and backing from Britain, Denmark, and other European countries.
The French-led effort to take back Mali’s north from the extremists occupying it has included airstrikes by jets and combat helicopters on at least four northern towns, of which Gao is the largest.
Some 400 French troops have been sent to the country in the effort to win back the territory from the well-armed rebels, who seized control of an area larger than France after a coup in Mali nine months ago.
The action coincided with a failed French attempt Friday to rescue a hostage held by Islamic militants in Somalia.
President Obama acknowledged Sunday that US fighter jets provided backup support to the effort.
The risky mission by French commandos ended disastrously after a gun battle with fighters from Al-Shabab militant network. The hostage, a spy identified by his cover name, Denis Allex, was presumed killed and a French soldier was reported missing.
Obama said the US warplanes briefly entered Somali airspace but did not open fire and departed Somalia by 8 p.m. Friday, Washington time. He gave no other details.
In Mali, the French Defense Ministry said its fighter jets destroyed several targets near Gao, including training camps, infrastructure, and logistical depots that it said were bases for terrorist groups.
Residents of Gao confirmed that the targets included the city’s airport as well as the building that served as the base for the town’s feared Islamist police, which — in their adherence to a strict version of Muslim law — have carried out numerous punishments including amputating limbs of accused thieves.
Gao resident Abderahmane Dicko, a public school teacher, said he and his neighbors heard the jets screaming across the sky between noon and 1 p.m.
‘‘We saw the war planes circling. They were targeting the camps uses by the Islamists. They only hit their bases. They didn’t shoot at the population,’’ he said.
But the intervention has come with a human cost in the city of Konna, the first to be bombed on Friday and Saturday. The town’s mayor said that at least 10 civilians were killed, including three children who threw themselves into a river and drowned trying to avoid the falling bombs.
President Francois Hollande of France authorized the military operation, code-named ‘‘Serval’’ after a sub-Saharan wildcat, after it became clear that the advancing rebels could push past the defenses in the town of Mopti, the first town on the government-controlled side, which has the largest concentration of Malian soldiers.
The decision catapulted the world and Mali’s neighbors into a military operation that diplomats had earlier said would not take place until at least September. France’s defense minister said they had no choice because of the swift rebel advance.
US officials said they had offered to send drones to Mali and were considering a broad range of options for assistance, including information-sharing and possibly allowing limited use of refueling tankers. Prime Minister David Cameron of Britain also agreed to send aircraft to help transport troops.
On Saturday, the body representing nations in West Africa announced that the member states would send hundreds of troops of their own, including at least 500 each from Niger, Burkina Faso, and Senegal, as well as from Nigeria.