The United States said it did not have independent information to confirm Nigeria's claim to know the whereabouts of more than 200 kidnapped girls.
It also questioned the wisdom of making public such information.
"We don't have independent information from the United States to support these reports you referenced," US State Department spokeswoman Jen Psaki said.
She was responding to a question about Nigerian Chief of Defence Staff Air Marshal Alex Badeh's statement that the military knew where the abducted girls were.
"We, as a matter of policy and for the girls' safety and wellbeing, would not discuss publicly this sort of information regardless."
Separately Boko Haram gunmen attacked a Nigerian military base and adjacent police barracks simultaneously in the northeastern town of Buni Yadi, killing at least 31 security personnel, security sources and witnesses said.
A witness said the militants arrived in an armoured personnel carrier and six pick-up trucks before dismounting and firing into the air.
They fired rocket propelled grenades at both bases.
A senior security source in Yobe state said 17 soldiers were confirmed killed and 14 police officers, including a female police officer, also died.
The attack late yesterday in Yobe state occurred not far from where the Islamist insurgents shot or burned to death 59 pupils at a boarding school in February.
In what has become rare for a movement that has killed thousands of civilians in the past year, Boko Harm called out to people on the street not to run away as they had only come for the security forces, a Yobe police source said.
The insurgents also razed the police barracks, the army base, the high court and residence of district head Abba Hassan.