MAIDUGURI, Nigeria (AP) — Thousands of refugees are fleeing northeast Nigeria into Cameroon, the U.N. refugee agency reported Wednesday, as extremists pursue a new strategy to hold land they are calling an “Islamic caliphate.”

Hundreds of Cameroonians also are abandoning their homes since Nigerian Islamic extremists last week began attacking villages in the neighboring country, UNHCR spokeswoman Helene Caux told The Associated Press.