Malian troops have recaptured the central town of Konna, which had fallen to Islamists rebels from the north a day earlier, a senior officer told AFP.
"Konna is under our control this (Friday) evening but we are still conducting mopping-up operations," Lieutenant Colonel Diarra Kone at the defence ministry told AFP. Some rebels might still be in the town, he warned.
Earlier, Mali backed by French airpower unleashed an offensive against Islamist rebels who have seized control of the north of the country and were threatening to push south.
President Francois Hollande confirmed in Paris that French forces were supporting an attack aimed at repelling Al-Qaeda-linked radicals who have triggered international alarm this week with moves towards the capital Bamako.
Mali's interim president Dioncounda Traore vowed to crush the country's "enemies" in a speech to the nation Friday evening as a nationwide state of emergency was declared that officials said would ban protests, meetings and public gatherings.
"Our choice is peace... but they have forced war on us. We will carry out a crushing and massive retaliation against our enemies," Traore said, while a military official said the offensive has put a stop to the rebels' advance.
"The Islamist advance has been stopped by the Malian army with the support of foreign troops. We are pursuing the offensive," said Captain Oumar Daw, who is based in Mopti, a strategically important central town near the frontline.
Malian officers said a key objective of the offensive was to retake Kona, a central town that was captured by Islamist forces earlier this week. They confirmed that initial exchanges had resulted in casualties on both sides.
"As in any war, the Malian army has suffered losses, the enemy also," Colonel Oumar Dao told a press conference.
The west African regional bloc ECOWAS also authorised its members to immediately send troops to Mali, and Dao said Nigerian and Senegalese forces were involved in Friday's offensive -- though Dakar denied having any troops in the country.
"No Senegalese soldier is on Malian territory," said Lieutenant-Colonel Adama Diop, from the public relations office at the Senegalese armed forces.
A Senegalese army official told AFP on condition of anonymity earlier that Senegal had "no combat forces" in Mali.
The Malian forces are, on their own, considered too weak and poorly organised to meet the challenge represented by the various Islamist groups who seized the north last year, taking advantage of the power vacuum created by a coup in Bamako.
Former colonial power France has warned that the Islamist rebels were seeking to transform the vast West African nation into a "terrorist state".
Hollande gave no indication of the scale of French involvement but said it would last "for as long as is necessary."
Foreign Minister Laurent Fabius said France's objectives were to stop the rebels' advance, ensure the territorial integrity of Mali and defend 6,000 French expatriates, who have been advised to leave the country.
Fabius confirmed that French airpower had been deployed in support of the offensive but was vague when asked if airstrikes had been carried out. "Was there an aerial intervention? Yes," he said.
'BRUTALITY AND FANATICISM'
African Union and Benin President Thomas Boni Yayi praised France for helping mount a counter-attack against the Islamist rebels and for recognising "the seriousness of the situation in Mali and West Africa."
Hollande authorised the deployment of French forces following an appeal for help from Traore, who will visit Paris for talks on Wednesday.
"Mali is facing a terrorist threat coming from the north, which the world knows for its brutality and fanaticism," Hollande said.
"France will always be there when it concerns the rights of a population that wants to live in freedom and democracy."
French Defence Minister Jean-Yves Le Drian briefed his counterparts in the United States, Germany and Britain, and all expressed public backing for the French move.
As well as capturing Kona, the rebel forces moved about 1,200 fighters to within 20 kilometres (12 miles) of Mopti, a town on the frontier between rebel-held and government-held territories.
Hollande said France's support for Mali's action was legitimate in international law and in line with the wishes of the United Nations.
The UN Security Council had already given its blessing for a 3,000-strong African force to be sent to Mali but it was not expected to be ready to deploy before September at the earliest.
Guinea on Friday urged the rapid deployment of the anticipated African-led force to Mali, where as Hollande pointed out the situation had become critical.
"They are trying to deliver a fatal blow to the very existence of this country," Hollande said. "France, like its African partners and the whole of the international community, cannot accept this."
The Islamists' advance towards the capital has exacerbated fears of Mali becoming an Afghanistan-style haven for extremists within easy reach of western Europe.
"Given the political situation in Bamako, it would not take much for the country to fall into the most total anarchy," Le Drian said.
Le Drian said he had been struck by the level of coordination and military organisation shown by the rebels at Kona.
US MULLS AID TO FRENCH IN MALI, INCLUDING DRONES
Meanwhile, the US military is looking at providing intelligence, aerial refueling tankers and other support to French forces in Mali, including surveillance drones, a US official said Friday.
Commanders were considering a range of options, including logistical backup and bolstering the sharing of intelligence, which would involve US surveillance drones, the official, who spoke on condition of anonymity, told AFP.
Backed by French air power, Mali on Friday unleashed an offensive against Islamist rebels who have seized control of the north of the West African country and are now threatening to push south.
President Francois Hollande confirmed in Paris that French forces were supporting an attack aimed at repelling the Al-Qaeda-linked radicals who have triggered international alarm with moves towards the capital Bamako.
Hollande gave no indication of the scale of French involvement, but said it would last "for as long as is necessary."
The American official told AFP that senior US officials were now engaged in discussions with their counterparts in the French capital and other allies on drawing up an action plan.
The American military has a network of air bases in Italy, Spain and elsewhere in the region that could provide refueling tankers and other assistance to the French.
Former colonial power France has warned that the Islamist rebels were seeking to transform the vast nation into a "terrorist state."
Earlier Friday, French Defense Minister Jean-Yves Le Drian briefed his US counterpart Leon Panetta about the situation.
