Nigeria suspended Twitter last June after the US company removed a post from President Muhammadu Buhari that threatened to punish regional secessionists.
Last month the Nigerian government said it was lifting the ban after Twitter had agreed to open a local office and work with the government to develop a code of conduct, among other agreements.
The Socio Economic Rights and Accountability Project (SERAP) said on Sunday it had filed a lawsuit to compel President Buhari and his information minister Lai Mohammed to publish a copy of the agreement to ensure it did not include agreements that could jeopardise freedom of expression.
"Publishing the agreement would enable Nigerians to scrutinise it, seek legal remedies as appropriate, and ensure that the conditions for lifting the suspension of Twitter are not used as pretexts to suppress legitimate discourse," a copy of the court challenge said.
SERAP said the government had ignored its request made in January for a copy of the agreement.
There was no immediate comment from the presidency and ministry of information.
Last June, SERAP and other groups went to court to fight the ban on Twitter, arguing that it was a violation of human rights.
The Court of Justice of the Economic Community of West African States is due to decide this week whether to go ahead and make a ruling on SERAP's challenge to the Twitter ban. The government, however, wants the court to throw out the case, arguing that it had been overtaken by events.
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