The mayor of Tripoli has disappeared, with city authorities saying he was kidnapped while other officials say he is in custody and being interrogated.
The Libyan capital’s municipal authorities say armed gunmen took Abdelraouf Beitelmal from his home.
However, public officials told the BBC he was being held and questioned for an unspecified crime.
Government and militia forces have vied for power in Libya since the uprising in 2011.
Sources close to Mr Beitelmal’s family told the BBC that gunmen had stormed the family home after midnight.
They claim the men fired at the house and beat Mr Beitelmal’s son with a Kalashnikov before taking the mayor away.
In a statement, Tripoli’s municipal council blamed “a foolish party” for the abduction, and said it was suspending its work in protest.
The council further said such acts “threaten the establishment of the state and its civilian life”.
However, Sediq AlSour, head of the investigations bureau at the attorney general’s office, told the BBC that the mayor was in custody and being interrogated by the by the General Investigation Directorate.
Mr AlSour did not give a reason for his detention, as his office is not in charge of the arrest.
Armed groups in Libya are known to threaten and attack government officials and civilians.
Moreover, it is often hard to assess the legality of an arrest because of the overlap between militias and government forces.
The country has been in chaos since Nato-backed forces overthrew longstanding ruler Muammar Gaddafi in October 2011.