The United Nations has warned that violence in north-western Nigeria has caused its citizens to flee into neighbouring Niger, where violence is also on the rise.

The UN refugee agency UNHCR said fear of armed groups and communal clashes in Nigeria had sent nearly 7,660 Nigerian refugees fleeing into Niger's southern Maradi region since the start of the year.

"Most of the refugees are women and children, displaced following recent attacks in Nigeria’s Sokoto state," UNHCR spokesperson Boris Cheshirkov said.

The Maradi region, in southern Niger, now hosts nearly 100,000 displaced people, including 77,000 Nigerian refugees, who have fled relentless attacks in Katsina, Sokoto and Zamfara states.

The UNHCR notes that armed groups in the Sahel and Lake Chad regions have been fuelling one of the world’s fastest growing displacement and protection crises, with millions displaced.