The US government is ready to loosen a ban on arms exports to Libya, in a bid to help the country's fledgling unity government fight the Islamic State group, officials and diplomats have told AFP.

Under White House-backed plans, the United Nations would carve out exemptions to an embargo introduced by the Security Council in 2011, during Moamer Kadhafi's failed attempt to suppress a popular uprising.

"If the Libyan government prepares a detailed and coherent list of things that it wants to use to fight ISIL and responds to all the requirements of the exemption, I think that Council members are going to look very seriously at that request," a senior administration official told AFP.

"There is a very healthy desire inside of Libya to rid themselves of ISIL, and I think that is something we should be supporting and responding to," the official said, using an acronym for the Islamic State group.

Kadhafi's regime was deposed with the help of NATO airpower in 2011 and he was ultimately killed in October of that year, but the country has been in turmoil since.

Dozens of militia groups have carved up the country into virtual fiefdoms, and two rival governments have been formed.

Western nations and many Libyans have watched in horror as the jihadist IS group has emerged from the chaos to control a swathe of central Libya around Kadhafi's hometown of Sirte.

With its port and airport, there are fears the jihadists could use the Mediterranean city as a staging post for attacks on Europe.

They have already hit nearby oil installations, choking much-needed oil revenues.

The Pentagon earlier this year estimated that as many as 6,000 Islamic State fighters were in the country, with a standing call for foreigners to join them.

US President Barack Obama's administration and its European allies have been eager to help the government establish itself and take on the jihadists.

When asked earlier this year about his greatest mistake in office, Obama cited Libya: "Probably failing to plan for the day after what I think was the right thing to do in intervening in Libya."

But the West has had to avoid the risk of appearing to interfere and, in so doing, undermining the fragile government.

- 'What are your needs?' -

Officials in Washington, Rome and elsewhere have recently toned down talk of sending a contingent of troops to the country to train and assist Libyan fighters, instead waiting for the government to request help.

"All the talk about what we might do, or could do, it responds to the needs of the Libyan government. When we talk about training or we talk about equipment, we are having a conversation about 'what are your needs?'" said the US official.

US actions in Libya have been limited to strikes against a suspected Islamic State training camp and a suspect believed to be involved in deadly attacks in neighboring Tunisia.

The US has also covertly sent a small group of special forces to Libya to gather intelligence and liaise with some militias, according to The Washington Post.

Loosening the arms embargo will be discussed when US Secretary of State John Kerry meets with his counterparts from regional powers in Vienna on Monday.

But it is not yet clear what weapons Libya might request and diplomats warn the government may struggle to come to that meeting with a concrete request amid factional fighting.

The UN-backed Government of National Accord is still very much a work in progress, struggling to extend its writ across Tripoli and the country.

Many militias refuse to come under government control, including those under the command of powerful renegade general Khalifa Haftar.

Officials and independent observers say that Haftar has received substantial military support from the United Arab Emirates and Egypt, calling the strength and utility of the embargo into serious question.

Other militias have been linked to Al-Qaeda.

If the arms embargo is to be eased, officials and diplomats say Prime Minister Fayez al-Sarraj will have to find a force both willing to fall under government control and battle jihadists who have shown they will fight to the death.

IS fighters, including two suicide bombers, on Thursday killed four Libyan fighters and wounded 24 in their latest foray into territory controlled by the government.

Sensing an attack may come soon, jihadists have begun pushing toward the coastal town of Misrata.

Sarraj's government will also have to address concerns about foreign arms falling into the wrong hands or fueling militia rivalries.

"There is no unified chain of command, there are still factional armed forces that are still more focused on fighting each other than on fighting ISIS," said Frederic Wehrey, a Libya expert at the Carnegie Endowment for International Peace.

"The real danger is that these factional militias would use the arms against each other."

Meanwhile the government has taken small steps to take control of ministries and begin to eke out a truly national military.

Earlier this week the government announced the creation of a "Presidential Guard" to protect government buildings, border posts, vital installations and VIPs.

"It's incremental progress, but it is tangible," said the US official.