Rumors of the death of Nigeria's most-wanted militant were proven wrong Sunday when video surfaced of Abubakar Shekau defiantly swearing, "We will not bring back your girls," referring to the schoolgirls kidnapped by Boko Haram in 2014.

The 30-minute video, posted online, features Shekau, the disputed leader of Islamic State-affiliated Boko Haram, flanked by masked and armed militants, ranting to the camera behind stacks of Qu'ranic texts. The video challenges recent reports that he'd been killed or injured in the offensive by the Nigerian military that re-took territory from the group, revealing a health crisis and mass starvation.

"This is Shekau; I am fine and healthy," he said in the video, according to a Nigerian blog that translated the video.

The video message comes after a number of setbacks for the Nigerian military in trying to quash the group. A round of attacks over the weekend killed seven Nigerian soldiers and wounded dozens more.

The militant group, once linked to al-Qaeda but now considered a province of the Islamic State's self-proclaimed caliphate — often going by the name Wilayat al Sudan al Gharbi — gained infamy after kidnapping hundreds of schoolgirls in Nigeria in 2014 and forcing many into slavery. While some have escaped or been rescued, it is believed that the group is still holding the majority captive.

"We will not bring back your girls," Shekau said in the video. "Bring back our own brethren."