The first lady's office denied there were any arrests.
Saratu Angus Ndirpaya of Chibok town said State Security Service agents drove her and protest leader Naomi Mutah Nyadar to a police station Monday after an all-night meeting at the presidential villa in Abuja, the capital.
She said police immediately released her but that Nyadar remains in detention. Deputy Superintendent Daniel Altine, police spokeswoman for Abuja, said she had no information but would investigate.
Ayo Adewuyi, spokesman for first lady Patience Jonathan, said there was a meeting but he was unaware of any arrests. "The first lady did not order the arrest of anybody, and I'm sure of that," he told the AP.
Police say more than 300 girls and young women were abducted April 15 from Chibok Government Girls Secondary School, of whom 53 girls escaped and 276 remain in captivity.