Indonesian police say gunmen have occupied two villages in easternmost Papua province near a U.S.-owned gold and copper mine in a possible escalation of a separatist conflict in the region.

Papua police chief Boy Rafli Amar said Thursday that about 1,300 people have been prevented from leaving the villages of Kimberly and Banti in the past two days by a group that includes about 25 armed men.

There has been an escalation in attacks on staff of the giant Grasberg mine and on paramilitary police in the past month.

A low-level insurgency has simmered in the provinces of West Papua and Papua for decades.