Some of thousands of Nigerians told to leave neighboring Niger in the past week due to threats from Boko Haram militants have died en route from lack of food and water, evacuees said.

Niger has evacuated Nigerians living around Lake Chad, military and aid officials told Reuters on Tuesday, as the armies of four West African nations battle to quash the Islamist militants.

"I counted over 50 people that died on our way out of (the town of) Lalewa when the Niger soldiers were chasing us as if we are animals," said 45-year-old Ibrahim, one of the group who was originally from Nigeria's Kebbi state.