The Nigerian army has been fighting to dislodge insurgents operating in the north-east.  Photo: Reuters

Nigerian military says its troops have rescued dozens of captives, mostly women and children, held by militants in the country’s hard-hit northeastern region.

In a statement on Monday, the army said 25 captives were rescued during "clearance operations" in Borno state’s Gwoza district.

The area is a hotbed of terror-related violence that has upended lives and livelihoods in the region since 2009, when the Boko Haram group launched an insurgency.

Fourteen of the captives were first rescued on Saturday in Gobara village, while 11 others were freed on Sunday when troops raided the militants' hideout in Gava village, both around 130 kilometres (80 miles) from the Borno state capital, Maiduguri, said army spokeman Onyema Nwachukwu.

Malnourished hostages

The army shared pictures of the freed hostages, which included toddlers. Most of them looked malnourished with worn-out clothes, suggesting that they might have been held for a long time.

"All rescued victims are presently in troops’ custody undergoing profiling," Nwachukwu said, describing the operations as part of the "unrelenting efforts to clear remnants of terrorist enclaves" in Borno and other states.

He said that seven Boko Haram fighters surrendered to troops on Sunday in a separate operation. They included three adults and four children.

At least 35,000 people have been killed and 2.1 million people have been displaced as a result of the extremist violence that has spread to neighbouring Cameroon, Chad, and Niger, according to data from U.N. agencies in Nigeria.