A bomb exploded outside a Nigerian court in Port Harcourt, the capital of the oil-rich River State, as judges were deliberating on the regularity of local elections.
No one was injured in the blast, which did not disrupt the proceedings that saw the federal high court dissolve the 22 local councils.
"I think they were trying to disrupt the result... the high court decided that the election was illegal," Governor Nyesom Wike said, Reuters reported.
"It [the blast] was close to the high court, nobody was killed and it didn't affect the building."
Separately, in Maiduguri, an embattled city on the opposite side of the country, commercial flights were resuming months after the local airport was shut over security concerns for the continuous attacks by Boko Haram.
The re-opening was a major step in attempts to bring the city back to normality despite regular deadly bombings hitting its streets and surrounding areas.
The move came weeks after President Muhammadu Buhari announced he was to relocate military headquarters from Abuja to Maiduguri, the biggest city in north-east Nigeria, as part of efforts to quell the six-year Islamist insurgency.