The Islamic State-allied faction of Boko Haram has reportedly expressed its willingness to negotiate the release of 83 more Chibok girls after freeing 21 of the more than 200 abductees last week.

According to the SABC, Presidential spokesperson Garba Shehu disclosed the development, adding that the Nigerian government was willing to broker a deal with the group.

The Islamist sect was alleged to have split into two factions after Abu Musab al-Barnawi was named leader of the sect by the Islamist State, sparking a backlash from long-time leader Abubakar Shekau.

"The faction said it is ready to negotiate if the government is willing to sit down with them," Shehu was quoted as saying.

The ISIS-allied splinter group said the rest of the kidnapped Chibok girls were with the part of Boko Haram under the control of Shekau, according to the report.