Fear of Boko Haram attacks has driven at least 7,000 people from Niger to seek refuge in Chad in the last week, and thousands more may cross the border if the violence escalates, the United Nations said on Monday.

The recent arrivals in Chad's Lake region felt compelled to leave Niger after attacks by Islamist Boko Haram militants on their village and neighboring communities in the southeastern Diffa region, according to the U.N. refugee agency (UNHCR).

Diffa has seen intense fighting over the past year between Niger's army and Boko Haram militants. The region hosts almost a quarter-of-a-million uprooted people, from Niger and Nigeria, who have been forced to flee their homes by the violence.