France has issued a warning against travelling to Niger after six French aid workers were among eight people killed by suspected fighters at the weekend.
The foreign ministry said on its website on Wednesday people were "strongly advised" not to travel anywhere in the country, excluding the capital, Niamey, for which travel was "not advised unless for compelling reasons".
The new advice means that the southern part of Niger, roughly a quarter of the country and far from areas where fighters are believed to operate, has been added to the so-called red zone, for which there is a strong recommendation to avoid.
"The terrorist threat against Niger, especially outside the capital and near the borders, is very high," the ministry said.
The French nationals - members of the NGO ACTED - their Nigerien guide and a driver were murdered on Sunday in the Koure National Park, a wildlife haven 65km (40 miles) from Niamey.
The assailants vanished without a trace and no group has claimed responsibility for the attack.
France has more than 5,000 soldiers deployed in the Sahel, an arid region south of the Sahara desert plagued by a worsening conflict that involves multiple armed groups, military campaigns by national armies and international partners as well as local militias.
The unrest began in 2012 when an uprising by Tuareg rebels in the north of Mali was swiftly hijacked by al-Qaeda-linked fighters. The presence of thousands of foreign troops has failed to stem the violence, which has spilled into neighbouring Burkina Faso and Niger, with groups exploiting the poverty of marginalised communities and inflaming tensions between ethnic groups.
As soldiers from both Niger and France combed the reserve and surrounding areas for signs of the attackers, French President Emmanuel Macron on Tuesday pledged to reinforce security measures in the Sahel, without elaborating. Meanwhile, Niger's government extended a state of emergency to the entire region that surrounds Niamey and suspended access to the giraffe reserve.
Nous mettons tout en œuvre pour soutenir les familles des victimes et répondre à l’attaque qui a coûté la vie à six de nos compatriotes et à deux Nigériens. Membres de l’ONG Acted, ces six jeunes témoignaient d'un engagement remarquable pour les populations.— Emmanuel Macron (@EmmanuelMacron) August 11, 2020
Translation: We are doing everything we can to support the families of the victims and respond to the attack that claimed the lives of six of our compatriots and two Nigeriens. Members of the NGO Acted, these six young people demonstrated a remarkable commitment to the populations, Macron wrote on Twitter.
The recent killings were the first by suspected fighters in the area, a destination for weekend leisure trips by Niamey residents, including foreigners.
Previously, Niamey and the town of Koure were marked as yellow under France's colour-coded security advice - a category that calls for additional vigilance but says the risk is "compatible with tourism".
Niamey is now classified as orange (travel "not advised unless for compelling reasons") while Koure, like the rest of the country, is in the red zone.
Although there has been no claim of responsibility, suspicion has fallen on the Islamic State in the Greater Sahara (ISGS), which has suffered recent losses at the hands of the French military.
"The barbarity and the conduct of the massacre do indeed bear the hallmarks of the ISGS," said Niagale Bagayoko, of the African Security Sector Network, a think-tank and advisory group.
The French army and its allies in the so-called G5 Sahel states of Burkina Faso, Chad, Mali, Mauritania and Niger have killed dozens of fighters in recent months, leading some to claim that the tide had turned against armed groups in the region.
But local and French forces still suffer regular attacks.
Accusations of abuses by local forces coupled with turmoil in Niger's vast neighbour Mali - where President Ibrahim Boubacar Keita is facing mass protests and demands to step down - complicate the fight against these groups.