The demonstrators also took control of the premises of Abu Slim Brigade, another independent militia force, besides storming into another base of Ansar.
The action against Ansar is considered a part of the coordination move by the police, government troops and activists to remove militia headquarters in the wake of mass protest against militia units earlier in the day. The protesters, who were shouting "Libya, Libya" and waved weapons, stormed the Ansar headquarters and pulled down militia flags and torched a vehicle.
The demonstrators, who were giving slogans against the al-Qaeda, said the people of Benghazi had witnessed enough of extremism. There was, however, no resistance on the militants' behalf. The base, which was stormed by the pro-government forces, was once the base of former leader Muammar Gaddafi. It was later taken over by Ansar.
Earlier, several Libyans marched in Benghazi, the second-largest city in the country, in support of democracy and against Islamist militias whom the US blamed for the attack on its consulate. Hundreds of Ansar supporters also held a counter-protest.
The demonstration, known as 'Rescue Banghazi Day', called for the government to take on armed groups that refused to surrender arms and weapons since the NATO-backed revolution that started last year.
(With agency inputs)