More than 37,000 people have fled violence between the army and Boko Haram insurgents in northern Nigeria for neighbouring Niger, the United Nations said Wednesday.

According to the latest report from the UN Office for Humanitarian Affairs (OCHA), “37,332 people fleeing clashes in the states of Borno, Yobe and Adamawa in the north of Nigeria have been registered in Diffa, southeast Niger”.

Nearly 29,000 people that have escaped were Niger nationals living in Nigeria while the rest are Nigerians. The number includes many women and children.

The number of refugees fleeing to Niger has increased sixfold since June, a month after the Nigerian army started a major offensive in the northeast aimed at crushing Boko Haram’s four-year insurgency, which has left thousands dead.

Borno, Yobe and Adamaoua all lie along the border with Niger.

The influx of refugees has strained resources in Niger, a country that regularly struggles with both droughts and flooding, and where a million people are currently facing food shortages.

Aid groups working in the area were organising food and water provisions, the UN said.

Refugees are “more and more in need of international protection”, said OCHA, urging Nigeria’s neighbours to “keep their borders open”.

Niger must quickly give refugee status to the thousands of Nigerians now on its soil, the UN added.

The US on Wednesday classed both Boko Haram, a radical Islamist network, and its offshoot Ansaru as terror groups.