At least seven people have been wounded in Libya’s eastern city of Benghazi when a car bomb exploded at a checkpoint manned by special military forces, according to the Reuters news agency.
Mohammed al-Hajazi, spokesman for the office that oversees security in Benghazi, said four soldiers and at least three civilians were wounded late on Tuesday.
Last week in the city, an army officer was killed by a bomb placed in his official vehicle.
Libya's authorities, who are struggling to form a professional army and police, regularly use former rebels to secure the borders or to intervene in tribal conflicts.
The government has failed to disarm and disband the former rebel groups who implement the law in parts of the country.
In a separate incident late on Tuesday an armed group attacked Libya's interior ministry building in the capital Tripoli, forcing its closure, witnesses said.
Armed men surrounded the building and blocked its entrance with sand before leaving the area.
"They were calling for the minister to resign because of his dependence on the Supreme Security Committee (SSC)” an interior ministry source told Reuters.
SSC, created after the country's 2011 war, is composed of militiamen, who are often better armed and more powerful than the police.
Several police guards said the armed group retreated when members of the SSC arrived to the scene.
Last week, some of the SSC's members clashed with a rival militia in Tripoli, highlighting the rivalries between heavily
armed groups roaming the country since the fall of Muammar Gaddafi.
That violence, in which 10 people were killed and more than 100 injured, led to the removal of the defence minister.