Lagos - A struggle in Nigeria's Islamic extremist group Boko Haram is playing out in public with a new leader named by the Islamic State accusing long-time leader Abubakar Shekau of killing his own people and living in luxury while fighters' babies starve.Abu Musab al-Barnawi, named by ISIS last week as the new governor of its so-called West Africa Province, alleged that Shekau had killed fellow Muslims including his own fighters, neglected hungry women and children, and failed to provide food and weapons to fighters.His audio message apparently was made on Friday and posted by the New York-based Sahara Reporters, a Nigerian newsgroup.Shekau responded in a video posted on YouTube, saying al-Barnawi is not qualified to lead the group but insisting that "we have not reneged on our loyalty to the leadership of (Abu Bakr) al-Baghdadi," the ISIS leader. The video, which was posted on Sunday night and removed by YouTube for violating its standards, ends with Shekau firing repeatedly in the air. He is flanked by two fighters hefting rocket-propelled grenade launchers.The video starts with an unidentified masked man in front of a large group of armed fighters announcing their refusal to follow al-Barnawi and calling Shekau "our leader."Then Shekau, with his trademark bushy beard and camouflage, threatens more attacks and warns "President (Muhammadu) Buhari, very soon you will see us inside your home, the presidential palace."The in-fighting could further weaken the Boko Haram militants, who are on the run from a multinational force in northeast Nigeria. The seven-year Boko Haram uprising has killed more than 20 000 people, forced 2.2 million from their homes and spread across Nigeria's borders.UN aid suspendedBoko Haram remains deadly, though it has not had a spectacular attack in nearly a year. Its ambush last month on a humanitarian convoy led the United Nations to suspend aid to newly liberated but still dangerous areas of the northeast where aid groups say about half a million people are starving.Shekau pledged allegiance to al-Baghdadi in March 2015, giving ISIS its first franchise in sub-Saharan Africa.Al-Barnawi's latest message says eight members of Shekau's "kitchen Cabinet" have revolted. It also indicates that the indiscriminate killing of Muslims, with numerous suicide bombings and shootings in mosques, lost Shekau the support of ISIS."You will see how he (Shekau) justifies and boasts of killing people. We are not killers like him," al-Barnawi says.Al-Barnawi has promised not to attack mosques or markets frequented by Muslims, but he has vowed to attack Christians and churches.He also claims to have spies among Shekau's bodyguards who will kill him if anything happens to him.