Three men burst into Nigeria's Senate on Wednesday and snatched the legislature's ceremonial mace, in an incident the body's spokesman blamed on a lawmaker who had been suspended.
The men entered the chamber, picked up the mace and left with it in a swoop that lasted less than two minutes. A Reuters journalist at the scene was not able to identify them.
The upper house of parliament resumed 15 minutes later after replacing the mace with a spare, the spokesman said.
Decisions taken in the Senate cannot be approved without the mace, an ornamental staff symbolizing the authority of the legislature. A giant statue of a fist holding a golden mace stands outside parliament, making it one of Nigeria's most potent government symbols.
"Today, some hoodlums led by suspended senator Ovie Omo-Agege walked into the Senate plenary and seized the symbol of authority of the upper legislative chamber, the mace," Senator Aliyu Abdullahi, spokesman for the upper house, said in a statement.
He later said the session had resumed.
Witnesses said the mace-snatchers drove into Senate premises in the company of Omo-Agege and passed through security unchecked.
The senator, who was suspended last week following a disagreement with other lawmakers, later appeared flanked by police at the parliament building.
"I am not under arrest. All the police here are for my safety," Abdullahi told reporters in the reception of the parliament building.
Political campaigning has cranked up a gear in Nigeria, the continent's most populous nation and top crude oil producer, ahead of presidential and gubernatorial elections early next year. President Muhammadu Buhari said last week that he will stand for re-election.
"This action is an act of treason, as it is an attempt to overthrow a branch of the Federal Government of Nigeria by force, and it must be treated as such," Abdullahi said. "All security agencies must stand on the side of due process and immediately mobilize their personnel to retrieve the mace and apprehend the mastermind and the perpetrators of this act."