ABUJA (Thomson Reuters Foundation) - Islamist militant group Boko Haram, which last week freed 21 of more than 200 Chibok schoolgirls it kidnapped in April 2014 in northeast Nigeria, is willing to negotiate the release of 83 more of the girls, the president’s spokesman said on Sunday.

Some of the 21 Chibok school girls released are seen during a meeting with Nigeria's Vice President Yemi Osinbajo in Abuja, Nigeria, October 13, 2016. Sunday Aghaeze/Special Assistant to Nigerian President Muhammadu Buhari/Handout via REUTERS

Around 220 girls were taken from their school in 2014 in Chibok in northeastern Borno state, where Boko Haram has waged a seven-year insurgency aimed at creating an Islamic state, killing thousands and displacing more than 2 million people.

The main faction of Boko Haram led by the group’s established figurehead Abubakar Shekau released 21 of the girls last week after the Red Cross and the Swiss government brokered a deal.

Boko Haram has split with a big group moving away from shadowy leader Shekau over his failure to adhere to guidance from the Iraq- and Syria-based Islamic State.

The part of Boko Haram under the control of Shekau said the rest of the kidnapped Chibok girls - estimated to be around 115 - were with the Islamic State-allied splinter group, according to Garba Shehu, spokesman for President Muhammadu Buhari.

“These 21 released girls are supposed to be tale bearers to tell the Nigerian government that this (Shekau) faction of Boko Haram has 83 more Chibok girls,” Shehu told the Thomson Reuters Foundation by phone.

“The faction (of Shekau) said it is ready to negotiate if the government is willing to sit down with them,” said Shehu, adding that the state is prepared to negotiate with Boko Haram.

Boko Haram last year pledged allegiance to Islamic State, which in August named Abu Musab al-Barnawi as the group’s leader for West Africa in its weekly magazine, al-Naba.

But that appointment was later dismissed in a 10-minute audio clip on social media by a man purporting to be Shekau, exposing divisions within the jihadist group that has plagued Nigeria and neighbours Chad, Niger and Cameroon.

Information Minister Lai Mohammed last week denied reports the state had swapped captured Boko Haram fighters for the release of the girls and said he was not aware if any ransom had been paid. He said a Nigerian army operation against Boko Haram would continue.

In recent weeks, the Nigerian army has been carrying out an offensive in the Sambisa forest, a stronghold of Boko Haram.

The militants controlled a swathe of land around the size of Belgium at the start of 2015, but Nigeria’s army has recaptured most of the territory. The group still stages suicide bombings in the northeast, as well as in neighbouring Niger and Cameroon.