Joe Ajero, the president of Nigeria’s largest labour federation, the Nigeria Labour Congress (NLC), was arrested by state security forces on Monday.
The charges against him remain undisclosed.
The arrest comes just days after Ajero criticized the government’s recent decision to increase gasoline prices by 39%.
He had threatened a nationwide strike if the government did not reverse the decision. High fuel prices have been a major factor in recent protests over the rising cost of living.
Ajero was apprehended by officials from the Department of State Security (DSS) at the airport in Abuja as he prepared to travel to Britain for union business.
The DSS has not yet issued a statement regarding the arrest.
Analysts fear that the latest fuel price hike, which will disproportionately impact small businesses and households reliant on generators, could further fuel inflation and exacerbate economic hardship in Nigeria.