French troops have begun direct ground combat against fighters belonging to the al-Qaeda-linked Ansar al-Dine group in Mali.
Quoting Sanda Ould Boumana, spokesman for Ansar al-Dine, Al Jazeera's Nazanine Moshiri reported from Bamako on Wednesday that the French forces had moved 400km north from the Malian capital and were shelling Diabaly, a town in central Mali.
She quoted Ould Boumana as saying that "the fighting is happening 2km from the centre of Diabaly, away from the civilians".
Ansar al-Dine fighters and their Tuareg allies occupied northern Mali in April 2012
"Military sources in the Malian army have told Al Jazeera that French special forces are fighting in the town," she said.
Edouard Guillaud, France's military chief of staff, said the French ground operations in the West African country began overnight.
Our correspondent said the military action was expected to be "difficult" for France.
"Ansar al-Dine and other armed rebel groups that have control of the area know the terrain very well, and they have very sophisticated weapons," she said, referring to the rebel-controlled northern part of Mali.
She said the first Nigerian contingent of about 190 soldiers was due to arrive in Mali on Thursday.
The parliament in Niger was waiting for approval to send its own contingent of more than 500 soldiers, currently waiting at the border, Al Jazeera's Moshiri said.
Diabaly residents who have fled the area told the Associated Press news agency that Ansar al-Dine fighters had sealed off the roads to the town and were preventing people from leaving.
They feared that the fighters would use the residents of the town as a human shield.
Rebels also clashed with Malian and French forces on Wednesday near Konna, a central town whose capture by rebels last week prompted France to launch its military offensive, security sources said.
"Fighting is under way not far from Konna between the Islamists and our army, with support from the French army," a Malian security source said.
A regional security source confirmed the information, but no details were available on the support from the French forces.
About 2,000 West African troops forming part of a regional intervention in Mali will arrive in Bamako within the next 10 days, official sources said on Wednesday.
Army chiefs of the Economic Community of West African States (ECOWAS) bloc met in Bamako to plot the deployment of up to 3,300 troops to shore up the French offensive.
"Urgency necessitates that everything is speeded up so that 2,000 men from AFISMA (African-led International Support Mission for Mali) arrive in Bamako before January 26," read an internal document from the meeting seen by AFP news agency.
The number was confirmed by Commander Abdoulaye Diakite from the Malian army.
"We have agreed to start by mobilising 2,000 men. Things will move fast because from tomorrow, the Nigerian army will send its first contingent," he said.
"Troops from other countries will quickly follow."
Francois Hollande, French president, authorised air attacks last Friday after Ansar al-Dine fighters began progressing towards Bamako from their northern stronghold.
The rebels seized the region in April 2012 amid the unrest that followed a coup in Bamako.
Speaking at a ceremony in Paris to give his New Year greetings to the press on Wednesday, Hollande said that he felt his decision on Friday had been "necessary".
"If it hadn't been taken, it would have been too late. Mali would have been captured entirely, and the terrorists would have been in a position of strength not only in Mali, but also able to put pressure on all countries of West Africa," he said.
Before tripling the number of French troops deployed in Mali to 2,500 from 800 on Tuesday, France had insisted that it would provide only air and logistical support for a military intervention.