LAGOS, Feb. 16 (Xinhua) -- Nigerian troops confronting Boko Haram insurgents in the restive northeast region have drilled a borehole in the terrorists' last enclave in Sambisa forest, a military spokesperson said on Friday.

The borehole was in addition to road rehabilitation projects to facilitate infrastructural development in the forest and adjourning communities, army spokesperson Sani Kukasheka said in a statement reaching Xinhua in Lagos.

He said the borehole was to enhance water supply to troops and communities in the area as part of efforts to make the forest habitable.

According to him, the project was carried out also as part of an ongoing clearance operation to root out remnants of Boko Haram insurgents.

Kukasheka said the army has constructed a borehole at the cleared insurgents' stronghold "Sabil Huda" camp in Sambisa forest to enhance the troops' access to safe drinking water.

The Nigerian army has embarked on rehabilitation of roads to open up the forest and link adjourning communities.

The Sambisa forest, especially the mountainous region of Gwoza near the Cameroon border, has been used as a shelter of the jihadist Boko Haram group.

Boko Haram has killed nearly 15,000 people and displaced over 2 million during a seven-year insurgency aimed at creating an Islamic state in Nigeria.

In recent years, its attacks have spilled into neighboring Niger, Cameroon and Chad.