(CNN) -- Islamist rebels in Mali acknowledged Sunday that they have suffered heavy losses in a battle against the military and French troops.
"This is a holy war. The deaths are normal," said Sanda Ould Boumama, spokesman for the rebel group Ansar Dine, which is linked to al Qaeda.
"Our fighters are prepared to die for our cause," he told CNN by phone.
One of the group's lieutenants, Iyad Ag Ghaly, was killed in the fight over the central town of Konna, security sources said.
Insurgents took the town on Thursday but retreated Friday after a combined air and ground assault.
"The war has only started," said Boumama. "We expect more casualties."
The military has sustained heavy losses as well. An effort to halt the rebels' advance caused "many deaths" in northern Mali, a military spokesman said Saturday.
Fatalities included Malian soldiers and a French pilot who was killed in a helicopter raid, the military spokesman said.
France, the country's former colonial ruler, recently sent several hundred troops to help the military in its battle against rebel forces. About 6,000 French citizens live in the country.
"There were many deaths on both sides, both rebels and government soldiers," Malian Defense Ministry spokesman Lt. Col. Diara Kone said Saturday. The government, in a statement read on state TV, said 11 of its soldiers died and about 60 were wounded in the battle for Konna.
"Every means was used in fighting the Islamists, including two attack helicopters. They sent the Islamists fleeing," Kone told CNN. "This shows that the Malian army is capable to fight."
The French pilot died while taking part Friday afternoon in an aerial operation targeting a terrorist group moving on the town of Mopti, near Konna, French Defense Minister Jean-Yves Le Drian said.
After decades of military rule, Mali held its first democratic elections in 1992. It remained stable politically until March, when a group of soldiers toppled the government, saying it had not provided adequate support for them to fight ethnic Tuareg rebels in the country's largely desert north.
Tuareg rebels, who'd sought independence for decades, took advantage of the power vacuum and seized swaths of land. A power struggle then erupted in the north between the Tuaregs and local al Qaeda-linked radicals, who wound up in control of a large area as the Tuaregs retreated.
The United Nations says amputations, floggings and public executions -- like the stoning of a couple in July, who'd reportedly had an affair -- became common in areas controlled by radical Islamists. They applied a strict interpretation of Sharia law by banning music, smoking, drinking and watching sports on television, and damaged Timbuktu's historic tombs and shrines.
Already, the armed groups' activity, along with a pervasive drought, has left hundreds of thousands of Malians displaced.
The Islamists' movement southward has raised concerns among leaders in West Africa and elsewhere, some of them calling for swift and decisive military intervention to aid Mali's government, based in Bamako.
The Economic Community of West African States plans to hold an emergency meeting in Abidjan, Ivory Coast, to prepare to send troops to Mali to help government forces, a spokesman for the organization said.
West African troops are expected to number 3,500 and will operate in the framework of the United Nations resolutions, ECOWAS spokesman Sunny Ugoh said.
The U.N. Security Council last month authorized a one-year military peacekeeping mission in the country. ECOWAS members pledged thousands of troops, and the Security Council has urged other nations to contribute forces as well.
British Prime Minister David Cameron agreed to "provide logistical military assistance to help transport foreign troops and equipment quickly to Mali," but no British personnel in a combat role, a Downing Street spokesman said.
France has been in contact with U.S. Defense Secretary Leon Panetta about the situation, Le Drian said.
The U.S. military is weighing options, including logistical support and intelligence sharing with France, according to a U.S. defense official who spoke on condition of anonymity because no decisions have been made.
"This is a serious issue, and ... the United States is committed to going after terrorists wherever they may be in order to protect American interests, but also those of our partners and allies around the world," Pentagon spokesman George Little said last week.