The Bayelsa State Gubernatorial Petition Tribunal has nullified the election of Governor Duoye Diri of Bayelsa State.
It ordered the Independent National Electoral Commission (INEC) to conduct a fresh election within 90 days.
The election was nullified based on a petition by the Advanced Nigeria Democratic Party, which argued that it was unlawfully excluded from participating in the election.
The tribunal ruling can, however, still be challenged at the appeal court.
Monday’s ruling comes two days after the tribunal dismissed three other petitions against the election of Mr Diri of the Peoples Democratic Party.
They were filed by the Alliance for Democracy (AD), the United People’s Congress (UPC) and the Liberation Movement (LM).