The French military used fighter planes and helicopter gunships to carry out a dozen operations over the weekend in Mali, while an extremist group threatened to carry out attacks against countries taking part in the intervention to oust the Islamists from their strongholds.

France said it had targeted "terrorist vehicles" in six of the strikes over the last 24 hours, and that the campaign against the militants was making progress.

French forces have extended their deployment northward from the central town of Markala, reinforcing their presence in the towns of Niono and Mopti, according to Col. Thierry Burkhard, a French military spokesman.

In an interview with France-5 TV, French Defense Minister Jean-Yves Le Drian said he wasn't aware of any civilian casualties.

He said the air strikes had caused "significant" - though unspecified - losses among the jihadists, and only minor skirmishes involved French forces on the ground.

Also Sunday, the extremist group behind the deadly hostage crisis in Algeria threatened more attacks against foreign targets if France does not bring an immediate halt to its military operation in Mali.

In a statement, the Masked Brigade warned of more such attacks against any country backing France's military intervention in Mali.

"We promise all the countries that participated in the Crusader campaign ... that we will carry out more operations if they do not reverse their decision," it said, according to a transcript released by SITE Intelligence Group.

France began its military offensive in Mali on January 11, and has said that African nations must take the lead though it could be some weeks before they are ready to do so.

On Sunday, France said that some 400 troops from Nigeria, Togo and Benin had arrived Sunday in Bamako to help train an African force for Mali. Troops from Chad, who are considered hardened fighters familiar with the desert-like terrain of northern Mali, also have arrived, Le Drian said.

A top official with the West African regional bloc said Sunday the cost of the African intervention could top $500 million.

ECOWAS Commission President Kadre Desire Ouedraogo, who gave an interview to state television in Ivory Coast, said the initial estimate "may vary depending on the needs" of the mission and the situation on the ground.

Dead and missing from siege at Algerian gas plant

At least 81 people have been reported dead, including 32 Islamist militants, after the bloody, four-day hostage situation at Algeria's remote Ain Amenas natural gas plant. Nearly two dozen foreign workers remained unaccounted for late Sunday.

Following is a list of the latest information from Algeria on the dead and missing:

The dead:

• 32 Islamist militants, according to the Algerian government.
• 23 hostages, according to Algeria. Confirmed dead so far include six from the Philippines, three from Britain, two from Romania and one each from the U.S. and France.
• 25 more bodies found Sunday, unclear yet whether they were hostages or militants, according to an Algerian security official.

The missing hostages:

• JAPAN: 10 Japanese working at the plant are unaccounted for, according to their employer JGC Corp.
• NORWAY: Five Norwegian employees of Statoil are still missing, the energy company said Sunday.
• BRITAIN: Three other Britons still missing and feared dead, the U.K. government said Sunday. Another British resident also feared dead.
• THE PHILIPPINES: Four Filipinos are still missing, a government spokesman said in Manila.
• MALAYSIA: Two Malaysians are missing, the government says.