Nigeria's Acting President Yemi Osinbajo has condemned the "takeover" of the parliamentary building earlier on Tuesday by masked gunmen linked to the spy agency as a "gross violation" of the rule of law, the presidency has said in a tweet.

Mr Osinbajo sacked the head of the Department of State Security Service (DSS), Lawal Daura, after the gunmen blocked lawmakers from entering the building.

No official reason was given for the blockade, but the intervention came after more than 50 lawmakers - including Senate President Bukola Saraki - switched their loyalty in recent weeks from the ruling party to the opposition.

Mr Osinbajo regarded it as "completely unacceptable", and all law enforcement officials who "participated in this travesty will be identified and subjected to appropriate disciplinary action", the presidency tweeted.