Two of the abducted Chibok secondary school girls have died from snakebite, according to an Associated Press report quoting a member of Boko Haram.
The group, in a video released by its leader, Abubakar Shekau, has claimed responsibility for the mass abductions of April 15.
An intermediary told AP Boko Haram was ready to negotiate ransoms for the girls.
He said two of the girls have died of snakebite while about 20 are ill, the news agency reported.
Christians among the girls have been forced to convert to Islam, the man, said to be an Islamic scholar, told AP.
Shekau has threatened to sell the girls. “I abducted your girls,” said the leader of Boko Haram. “By Allah, I will sell them in the marketplace.”