Boko Haram is fracturing as shortages of weapons and fuel foment tensions between its foot soldiers and leaders, according to women rescued from the Islamist jihadi fighters by Nigerian troops.

The group abducted an estimated 2,000 women and girls last year as it sought to carve out an Islamic state in the northeastern sector of Africa's biggest economy. The army has freed nearly 700 in the past week as it advances on Boko Haram's last stronghold in the vast Sambisa forest.

The militants began complaining to their captives about lacking guns and ammunition last month, two of the women said, and many were reduced to carrying sticks while some of their vehicles were either broken down or lacked gasoline.