Libya's defence minister was the first cabinet minister to quit in a crisis over the siege, which armed groups refused to lift even after parliament bowed on Sunday to their main demand by banning from government posts any senior official who served under Gaddafi.
"I will never be able to accept that politics (can) be practiced by the power of weapons ... This is an assault against the democracy I have sworn to protect," Defence Minister Mohammed al-Bargathi said.
Members of parliament in Libya, plagued by armed disorder since Gaddafi's demise, say the new legislation could be applied to around 40 of 200 deputies and could also unseat the prime minister, who some protesters demand should quit immediately.
Diplomats fear that parliament, in agreeing to vote under duress, could effectively embolden the powerful armed groups that fought to topple Gaddafi and are now more visible in Libya than state security forces, and that the sweeping terms of the vote could cripple the government's ability to function.
On Monday a spokesman for parliament conceded that the siege of the ministries was out of the government's hands and that it would be up to the militiamen now to leave as promised.