Gunmen pressed their siege of two Libyan ministries on Wednesday, leaving the authorities in a dilemma of whether to risk a bloody confrontation or reinforce the image of a helpless state by negotiating patiently.
They have encircled the foreign ministry since Sunday and the justice ministry since Tuesday, demanding the sacking of former officials from the ousted regime of Moamer Kadhafi.
The same groups, most of them former rebels who fought to oust Kadhafi in 2011, briefly occupied the finance ministry on Monday.
On Sunday, former rebels who had once been responsible for security at the headquarters of Libyan national television, blockaded it although broadcasts were not interrupted.
And angry policemen invaded the interior ministry twice, on Monday and Tuesday, to demand higher pay and promotions.
On Wednesday, vehicles equipped with anti-aircraft guns and rocket launchers blockaded the foreign and justice ministries as traffic flowed smoothly on the May Day holiday.
"The siege of the foreign and justice ministries is continuing and will go on until our demands are completely satisfied," Aymen Mohammed Abudeina, a member of a group committed to ensuring the exclusion of former Kadhafi officials from public life, told AFP.
The justice ministry has dismissed the idea of using force to break the siege, saying the government preferred to "let wisdom prevail."
The government regularly promises firmness against these militias, and a campaign was recently launched to dislodge them from several public and private properties.
But the authorities avoid any use of force despite repeated attacks against state institutions by former rebels.
"In a tribal society such as Libya, any victim could trigger a deadly conflict," warned an official on condition of anonymity.
"The situation could escalate by just a spark."
On Tuesday, Justice Minister Salah al-Marghani explained the inaction of the government, saying "we want to save lives."
But Fathi Tarbel, a former minister in the transitional government and human rights activist, said that "weakens the authorities and gives an image of an incompetent and weak state."
He called the sieges sheer "banditry".
The General National Congress (GNC), Libya's highest political authority, has been studying proposals for a law that would see top figures from the Kadhafi regime sacked from their posts.
That has caused a stir among Libya's political elite, as several current senior officials could be affected.
Under increasing pressure from demonstrations, the GNC said on Monday that it was suspending plenary sessions until Sunday.
It said the delay was needed to give political blocs in the GNC time to examine the bill to reach a compromise on the law.
GNC Vice President Salah al-Makhzoum said a compromise had been reached among the political blocs by adding "exceptions" in the bill in order to retain key individuals.
He said the bill is expected to be voted upon next week.
Several observers say armed groups were using the law only as a pretext because their interests were threatened by the new authorities.
"Their reaction is proof that the plan implemented by the government of (Prime Minister) Ali Zeidan to dissolve the militias is on track," said a Western diplomat on condition of anonymity.
Political analyst Ezzedine Akil said "these former rebels feel marginalised and that they have achieved nothing from the revolution."
Since the fall of Kadhafi's regime, the former rebels managed border controls, prisons, strategic facilities in the country and vital institutions.
They received salaries and other perks from the authorities, and benefitted from smuggling and extortion.
But Amnesty International said the militias were now realising that they too are answerable.
"The era when the thuwwar (revolutionaries) were treated as untouchable heroes and placed on pedestals seems to be over, and their attempts to cover up abuses might be a sign that they finally realise that they will not remain immune from justice forever," the rights group said.