Boko Haram leader Abubakar Shekau made the claim in a new video on Friday, in which he also said that all the girls had converted to Islam and rejected claims of a ceasefire and peace talks.
The head of the Chibok Elders Forum in the northeast Nigerian town, Pogo Bitrus, said on Saturday: "It (the claim about marriage) is shocking to us, although we know that Boko Haram is not a reliable group.
"We were sceptical about the talks to release our girls and we never took the ceasefire seriously because since the announcement, they have never stopped attacking communities.
"Therefore the information that our girls have been married off is not surprising to us," said Bitrus, whose four nieces are among the hostages.
"We are only hoping the government will step up whatever efforts it is making to quell the insurgency."
Nigeria's military and presidency said on October 17 that they had reached a deal to end five years of deadly violence in the country's northeast, as well as agreement to release the Chibok girls.
But violence has continued unabated, including a triple bomb attack on a bus station in the northern city of Gombe on Friday, which killed at least eight and injured dozens more.
Shekau indicated in earlier video messages that the girls would be sold as slave brides and that some, but not all, had converted to Islam.
His latest claim that they were now all Muslims and had been "married off" chimes with testimony from former hostages that forced conversion and marriage are commonplace in Boko Haram camps.
