Ahmad Salkida, a Nigerian journalist, said he had negotiated for the girls' release on behalf of the government, but several opportunities to have them freed had been missed.
The Nigerian government said there was no reason to think some may be dead.
A spokesperson told the media that the government was still in discussions with Boko Haram to secure the release of the 112 girls who remain missing.
Mr Salkida said the administration of former President Goodluck Jonathan had asked him to negotiate for the release of the Chibok schoolgirls 2⃣ weeks after they were abducted. He said he had arranged for a prisoner swap on 5 occasions, but delays from the then government led to a breakdown in negotiations
Mr Salkida would not reveal the names of the remaining girls, stating that this was the responsibility of the Nigerian government.