Suspected Boko Haram militants riding motorbikes stormed two ​villages in northeast Nigeria, killing at ‌least 20 people, a local official said on Wednesday.

The assaults are part of a surge ​by Boko Haram and its Islamic ​State splinter ISWAP, who have stepped ⁠up deadly attacks on military bases ​and villages in Nigeria's insurgency-hit northeast.

The gunmen ​raided the villages of Pubagu and Mayo-Ladde in the states of Borno and neighbouring Adamawa, respectively, ​on Tuesday afternoon after overwhelming local ​vigilantes, said Mada Saidu, chairman of Askira-Uba district, ‌where ⁠one of the attacks occurred.

At least 11 people were killed in Pubagu and nine in Mayo-Ladde. Homes and shops were ​torched and ​food ⁠supplies looted, Saidu said.

Islamist militants have waged a 17-year insurgency ​seeking to carve out an Islamic ​state ⁠in northeast Nigeria, killing thousands and displacing at least 2 million people, aid ⁠groups ​say, despite major military ​campaigns to root them out.