A French pilot died on Friday when his helicopter was shot down near the central Mali town of Mopti. Hours later, in Somalia, a bid to rescue a French hostage held by Islamists failed and Paris said it believed the man had died in the raid.
The West African regional bloc ECOWAS has for months lobbied world powers to back its plan to end the nine-month occupation of Mali's north by Islamist groups Ansar Dine, MUJWA, and AQIM, al Qaeda's North African affiliate.
Ivory Coast's President Alassane Ouattara currently holds the rotating chairmanship of ECOWAS.
"The mandate for the deployment was signed by the president yesterday," said Ali Coulibaly, Ivory Coast's African Integration Minister.
"Monday by the latest, the troops will be there or will have started to arrive."
Malian soldiers recaptured a central town on Friday after France intervened with air strikes to halt a southward advance by the Islamist insurgents.
Western governments, particularly former colonial power France, voiced alarm after the rebel alliance captured the town of Konna on Thursday in their first major drive towards the capital Bamako since seizing control of the north last spring.
Mali's government appealed for urgent military aid from France. The Islamist offensive also threatened the town of Sevare, home to a military base and a gateway on the route to Bamako, around 500 km (300 miles) to the south.
"Things are accelerating ... This is not a mission to simply protect Sevare. We need to retake the northern part (of Mali) from the jihadists," Coulibaly said.
"The reconquest of the north has already begun."
French aircraft continued strikes against Islamist rebels in Mali on Saturday.
Defence Minister Jean-Yves Le Drian said French army units attacked a column of rebels heading towards Mopti. A French pilot was killed on Friday when his helicopter was shot down near the central town.
Le Drian said France had sent special forces into Mopti ahead of the intervention, to prepare the ground, and "several hundred" troops into the capital Bamako.
France had more Rafale fighter jets on standby to be deployed, Le Drian said.
Army chief Edouard Guillaud said however France had no current plans to extend operations to northern areas controlled by the Islamists.
President Francois Hollande on Friday said France would not stand by to watch the rebels push further south. Paris has repeatedly warned that the Islamists' seizure of the north gives them a base to attack neighbouring countries and Europe.
"We are faced with blatant aggression that is threatening Mali's very existence. France cannot accept this," Hollande, who recently pledged Paris would not meddle in African affairs, said in a New Year speech to diplomats and journalists.
The president said the U.N. Security Council resolutions meant France was acting in accordance with international law.
French military operations in support of the Malian army against Islamist rebels "will last as long as necessary," France's U.N. ambassador Gerard Araud wrote in a letter to the Security Council obtained by Reuters.
France's intervention immediately tipped the military balance of power, with Malian government forces quickly sweeping back into Konna, according to local residents.
The forceful French military action in Mali came as an attempt to rescue a French hostage in Somalia failed.
The Defence Ministry said it believed an intelligence officer held hostage since 2009 was killed along with at least one French soldier during the raid by French troops on Friday night.
But the Harakat Al-Shabaab Al-Mujahideen insurgent group who were holding Denis Allex said in a statement he was still alive and being held at a location far from the base where French military helicopters attacked overnight.
EU SPEEDS UP DEPLOYMENT
EU foreign policy chief Catherine Ashton called on Friday for "accelerated international engagement" and said the bloc would speed up plans to deploy 200 troops to train Malian forces.
A U.S. official told Reuters the Pentagon was weighing options including intelligence-sharing with France and logistics support.
Military analysts voiced doubt, however, whether Friday's action heralded the start of the final operation to retake northern Mali - a harsh, sparsely populated terrain the size of France - as neither equipment nor ground troops were ready.
"We're not yet at the big intervention," said Mark Schroeder, director for Sub-Saharan Africa analysis for the global risk and security consultancy Stratfor. He said France had been forced to act when the Islamists bore down on Sevare, a vital launching point for future military operations.
"The French realised this was a red line that they could not permit to be crossed," he said.
STATE OF EMERGENCY
More than two decades of peaceful elections had earned Mali a reputation as a bulwark of democracy - an image that unravelled in a matter of weeks after a military coup last March that paved the way for the Islamist rebellion.
Interim President Dioncounda Traore, under pressure for bolder action from Mali's military, declared a state of emergency on Friday. Traore will fly to Paris for talks with Hollande on Wednesday.
"Every Malian must henceforth consider themselves a soldier," Traore said on state TV, calling on mining and telecoms companies to contribute to the war effort. He said he requested French air support with the blessing of West African allies.
The French Foreign Ministry stepped up its security alert on Mali and parts of neighbouring Mauritania and Niger on Friday, extending its red alert - the highest level - to include Bamako. France has eight nationals in Islamist hands in the Sahara after a string of kidnappings.
A spokesman for al Qaeda's north African arm AQIM urged France, in a video posted on the Internet, to reconsider its intervention. "Stop your assault against us or you are digging your own sons' graves," said Abdallah Al-Chinguetti.
(Additional reporting by Joe Bavier in Abidjan; editing by Andrew Roche)