Former presidential candidate and activist, Omoyele Sowore, has been released after four months in detention.
A judge in Abuja ordered the Department of State Security (DSS) to free Sowore and pay a fine for their repeated refusal to comply with court rulings on the case.
The police had previously refused to grant him bail, despite being told to do so.
Mr Sowore, who is the publisher of the news site Sahara Reporters, was arrested in early August after calling online for an anti-government protest under the hashtag #RevolutionNow.
He has pleaded not guilty to treason, money laundering and cyber-stalking.