Libya gunmen surround Tripoli foreign ministry
Men in pick-up trucks bristling with anti-aircraft guns have blocked off Libya's foreign ministry, demanding a jobs ban on Gaddafi-era officials.
Dozens of armed men stopped workers entering the building and moved traffic away from the area, witnesses said.
Libyan officials have been unable to agree the terms of a law barring figures from the late Col Gaddafi's government from entering politics.
Armed groups have responded by storming the Congress on several occasions.
Prime Minister Ali Zeidan, at a news conference, urged Libyans to back their government in the face of "people who want to destabilise the country".
He also complained of other attacks and "acts of sabotage", carried out by separate groups, against the interior ministry and national TV headquarters. But Libya's Lana news agency said the action at the interior ministry was not linked to the events outside the foreign ministry.
Young and old
Roads leading to the building in the capital, Tripoli, were obstructed by at least 20 vehicles, as militiamen carrying AK-47 rifles moved into the area, although they did not enter the ministry itself.
There was a mix of men, young and old, some in civilian clothes and others wearing army fatigues, BBC Libya correspondent Rana Jawad reported from the scene.
They had no clear leader, but said they would remain until their demands were met.
The image of an armed brigade blocking access to a public building had so far usually been reserved for Libya's legislature, our correspondent said.
In March, protesters barricaded members of the General National Congress inside the building for hours, insisting they adopt the law keeping former Gaddafi-regime figures out of politics.
But the gunmen outside the foreign ministry complained that some senior roles in the foreign ministry were still filled by former regime officials.
Since Col Gaddafi's death, Tripoli and other Libyan cities have been plagued by violence and infighting.
The government has recently tried to dismantle illegally-armed militias that formed during and after the war that toppled the former leader.
Last week, the French embassy in the capital was targeted by a car bomb that left two French guards wounded and caused serious damage.