Tripoli. 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.The BBC’s Rana Jawad in Tripoli says the image of an armed brigade blocking access to a public building has so far usually been reserved for Libya’s legislature.In March, protesters barricaded members of the General National Congress inside the building for hours, insisting they adopt the law.On Sunday, roads leading to the foreign ministry 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.A man identifying himself as their leader told Reuters news agency that the ministry would remain shut until the political isolation law was passed.The gunmen say some senior roles in the foreign ministry are still filled by former officials from the Gaddafi era.The government has recently tried to dismantle illegally-armed militias that formed during and after the war that toppled Col Gaddafi in 2011.Since his death, Tripoli and other Libyan cities have been plagued by violence and infighting.Last week, the French embassy in the capital was targeted by a car bomb that left two French guards wounded and caused serious damage.