An Al Qaeda source has confirmed the death of one of the leaders of the organisation's north African wing, in the most significant success yet for the French-led operation against Islamist fighters in Mali.
But there were no public celebrations in Paris on Monday as relatives of hostages held in the region voiced fears the development leaves their loved ones at greater risk and called for a pause in the bombing to allow for negotiations aimed at securing their release.
Abdelhamid Abou Zeid, a senior figure in Al Qaeda in the Islamic Maghreb (AQIM), was killed last week in a French bombing raid in the Ifoghas mountains, an AQIM militant told the private Mauritanian news agency Sahara Medias.
The source insisted however that another Islamist leader, Mokhtar Belmokhtar, was alive and still fighting.
That contradicted claims over the weekend from Chad that its troops had killed Belmokhtar, the mastermind of the January assault on an Algerian gas plant in January that left 37 foreign hostages dead. Chad has also said its troops were responsible for killing Abou Zeid.
A French broadcaster on Monday published a cell phone picture which it said showed the bloodied body of Belmokhtar.
Radio France Internationale said the picture, reproduced on its website, was taken by a Chadian soldier in northern Mali.
With foreign governments reacting cautiously to Chad's claims about the deaths of the top militants, Chadian President Idriss Deby Itno on Monday said his country had only refrained from showing the bodies out of respect for Muslim customs.
The Al Qaeda source's acknowledgement of Abou Zeid's death came as France's top military official claimed that the intervention launched in January was breaking the back of AQIM and its allies in Mali.
It also coincided with a call by relatives of four of the French hostages held in the region for a pause in the bombing to allow for negotiations with the rebels on the possible release of their loved ones.
Fears the hostages may have been used as human shields or could be subject to reprisal executions have intensified in recent days as the reports on Abou Zeid and Belmokhtar emerged from Chad.
Abou Zeid was believed to have been holding four French citizens kidnapped in Niger in 2010, but the French army's chief of staff, Admiral Edouard Guillaud said that could not be confirmed.
Pascale Robert, the grandmother of Pierre Legrand, one of the four French nationals seized in Niger, urged the French president to "declare a pause in the conflict to allow for talks with the remaining figures, rather than fighting on blindly".
France's defence minister said Monday there was "every reason to believe" French hostages being held in the Sahel were still alive, while adding that there was "no proof" that two top Islamist militants had been killed in Mali.
Jean-Yves Le Drian said he understood "the anguish of the families and their pain", while insisting that France was operating "with respect for the lives of the hostages".
Although the hostage issue continues to cast a cloud over the campaign, French defence officials are happy with its progress.
Guillaud told reporters in Paris that good progress had been made in dismantling what he described as "an industrial terrorist organisation," with French forces having seized more than 50 weapons caches, a dozen workshops and 20 improvised explosive devices.
"It shows that this goes beyond... Mali, beyond even the Sahel, it was expansionist," he said.
"We have cleaned out one of the valleys, a main valley where Chadian and French forces moved in about 10 days ago," he said. "We searched all night and from today we will move into the other valleys.
"We are breaking the back of Al Qaeda in the Islamic Maghreb, that was the goal set by the president," he said.
Chad's President Deby said Monday that 27 Chadian soldiers had died in clashes with Islamists in northern Mali since late February, while "more than 70 terrorists" had been killed.
The Chadian army added that eight Islamist militants had been taken prisoner in battles in the Ifoghas mountains.
British Foreign Secretary William Hague meanwhile vowed continued support for Mali's fight against Islamists as he paid his first visit to the country.
"I welcome the progress made by French, Malian and African military forces in the north of Mali. The UK will continue to support this tough security response, including through the EU training mission," he said during the surprise one-day visit.
Britain is not sending combat troops to Mali, but it has provided logistical support and is due to deploy 40 personnel for the European Union training mission in the country.
Also on Monday, Mauritanian President Mohamed Ould Abdel Aziz said he would not rule out contributing to a UN force "to provide stability and security" in northern Mali if the situation improves.