France was forced to defend its allies in the Malian army after two human rights organisations said they had confirmation of reports of summary executions of suspected rebel sympathisers by Malian troops as they regained territory lost to Islamist fighters this week.

The French defence minister, Jean-Yves Le Drian called on Bamako to make sure its troops were “under control”. The Malian government issued a statement reminding the army to “show strict respect of human rights... There is no question of us condoning the same kind of actions which we condemn when committed by the terrorists”.

The first elements of a promised 3,000 strong, pan-west African force began to deploy in central Mali allowing Malian and French troops to push north towards the large rebel-held towns of Timbuktu and Gao. A force of 160 troops from neighbouring Burkina Faso relieved French troops guarding a bridge over the Niger river south of the town of Diabaly recaptured early this week.

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Further east French bombers targeted the town of Ansongo, about 80km from Gao, and also struck rebel camps in the nearby village of the Seyna Sonrai. “French military planes successfully attacked Islamist positions at Ansongo and nearby areas,” a Malian source said. “The strikes were very successful and caused damage to the enemy.”

The news of the Malian atrocities emerged as France edged closer to intervening in a second country in the Sahara-Sahel region. French special forces have been ordered to guard uranium mines run by the French state-owned nuclear company, Areva, in Niger. A source in Paris said that the deployment was a precaution following the mass hostage-taking at a gas complex in south eastern Algeria last week. Uranium from Niger provides a large part of the raw material for French nuclear power stations, which generate 75 per cent of the country’s electricity.

Troops and equipment would be sent to Areva’s uranium production sites in Imouraren and Arlit very quickly, the source added. Seven workers, including five French nationals, were kidnapped in Arlit by al-Qa’ida in the Islamic Maghreb in September 2010. It later released three of the hostages but four are still captive.

An official at the defence ministry said that for the moment Nigerien authorities had not yet approved the measure. A Niger army officer added that there were security arrangements agreed with France in 2011 after the kidnappings in Arlit and they had been reinforced over time. “For now, I don’t know of a decision by the Nigerien government to allow French special forces to base themselves in the north,” he said.

Part of one of the two Malian rebel groups, Ansar Dine, announced that it was breaking away to “control our own fate”. The group’s former leader, Alghabass Ag Intalla , said that he was creating a new organisation called the Mouvement islamique de l’Azawad (MIA).

“We are a group of people from the north of Mali who have a set of grievances that date back at least 50 years,” he said. “We are not terrorists. We are ready to negotiate.”