A lawyer Modupe (Moe) Odele says her passport is still with federal authorities.
The End SARS advocate was stopped from boarding her international flight on Sunday.
Odele said she was detained and her passport seized by officers.
Meanwhile earlier in the day, the Ministry of Interior said it was not targeting citizens.
“The Ministry of Interior did not, has not and will not generate any no-fly list. Ignore fake news, please!”, it tweeted.