NIGER has declared three days of national mourning following the massacre of 100 civilians in two villages in the western region of the country where Islamist militants have carried out a series of attacks. The government said an investigation had been launched to find the perpetrators. Witnesses have said that over a hundred armed assailants on motorbikes surrounded the villages and started firing indiscriminately on Saturday. The government said reinforcements had been sent to the area near the tri-border region of Niger, Burkina Faso and Mali known as Liptako-Gourma, where local authorities have been overrun by militants linked to al…