Security forces braced for protests Friday against Libya’s protracted political transition following the ouster of longtime dictator Moamer Gaddafi, with fears of more violence after an overnight attack on army headquarters.

Security forces braced for protests Friday against Libya's protracted political transition following the ouster of longtime dictator Moamer Gaddafi, with fears of more violence after an overnight attack on army headquarters.

Tensions have risen after a decision by Libya's highest political authority, the General National Congress, to extend its interim mandate.

Rival camps, many of them armed, have lined up for and against the GNC and its decision.

Interim Interior Minister Seddik Abdelkarim, who escaped an assassination bid late last month, issued an order late Thursday for security forces to "protect peaceful demonstrators."

But the "No Extension" movement, which has sponsored a number of recent demonstrations demanding the GNC's dissolution, is so concerned about the risk of violence that it was not formally organizing any protests on Friday.

A statement said any of its backers demonstrating would be doing so "as individuals expressing their opinions."

One member of the group said that, "given the current tensions, we cannot guarantee the security of demonstrators... With so many armed groups, we fear things could get out of hand."

No announcements have been made about where any demonstrations may take place, but they are expected after midday prayers on the Muslim day of rest.

The growing insecurity in Libya more than two years after Gaddafi's ouster and killing, was highlighted in the capital late Thursday, with a military spokesman saying unidentified gunmen had tried to enter army headquarters but guards prevented them from doing so.

"The attackers ransacked cars and stole some weapons before pulling back," Colonel Ali al-Sheikhi told AFP of the incident, in which no one was hurt.

A separate military source gave a different version of events, saying fighting broke out after a dispute among soldiers.

The GNC was elected in July 2012 for a term of 18 months that should have ended on Friday. But on Monday, it ratified a decision to extend its mandate to December.

It took the decision despite the opposition of much of the population critical of its inability to halt Libya's slide into lawlessness and chaos.

Political activist Abu Bakar al-Badrid described the move as "a farce... About 40 initiatives were presented to the Congress these past few days to find a way out of the crisis, and it paid no attention."

The Operations Cell of Revolutionaries, an Islamist militia of ex-rebels said to be close to the army, has lined up behind the GNC, and the powerful armed groups from Libya's third city Misrata have called the body "a red line."

But rival former rebels from Zintan, in the mountains southwest of Tripoli, an influential force in post-Gaddafi Libya, have vowed to protect any popular movement that goes against the GNC.

The GNC's mission has been to organize elections to a constituent assembly later this month which are to be followed by a general election.

The assembly, to be made up of 60 members with equal representation for Libya's three historic regions, will decide on key issues in a new constitution, including the system of government, the status of minorities and the role of Islamic Sharia law.

The political bickering comes at a time of uncertainty over the fate of independent Prime Minister Ali Zeidan.