LONDON: Mustafa Abu Shagour will be spending much of his time as Libya’s prime minister grappling with the country's grave domestic security problems, which have been painfully highlighted by the assault that killed the US ambassador in Benghazi.

Abu Shagour, a US-trained optical engineer who is admired for his negotiating skills, clinched victory by just two votes on Wednesday night over the better-known Mahmoud Jibril, architect of the rebel opposition and

lobbyist for the Nato intervention that helped overthrow Muammar Qadhafi last year.

Libya's first democratically elected leader presents himself as a unity candidate who will work with liberals, Islamists and independents when he takes office next month.

Problems await at every turn but at the top of his intray is the need to impose central government authority over the groups of thuwar (revolutionaries) who control separate fiefdoms and have largely refused to lay down their weapons more than a year since Tripoli fell.

Efficient delivery of basic services, long-term economic development, oil exports, foreign investment, a lack of strong institutions and transitional justice also require urgent attention. Political infighting and drawing up a new constitution are taking up time and effort.

Libya has suffered from serious insecurity in recent months. Incidents include clashes between rival brigades, revenge attacks against Qadhafi loyalists and ordinary disputes settled by force because the judicial system is not functioning.

Early efforts to create a national army and police force gave way to a practice of subcontracting security to militias whose commanders were ordered to quell tribal fighting in the western mountains and Saharan towns. During the July election, ballots were counted at the headquarters of Benghazi's strongest militia.

“The strategy of trying to dismantle the regional militias while simultaneously making use of them as hired guns might be sowing the seeds for the country's descent into warlordism,” the Carnegie Endowment's Frederic Wehrey warned in a recent article.

Little is known about the Ansar al-Sharia group in Benghazi, which was reported to have demonstrated at the US consulate over the blasphemous film, though it claimed it took part in a “spontaneous popular uprising”. The group denied targeting the US ambassador.

“This is not sustainable,” said Robert Malley of the International Crisis Group (ICG), whose new report on Libya highlights the challenges ahead. “The new government needs to take concrete steps to reform its security forces and establish structures of a functioning state. Anything less will perpetuate what already is in place: local disputes . . . in a fragmented and heavily armed landscape.”

Shagour has said that security is his number one priority but linked this to the need to create jobs for young people.

Pressure from the US and European allies such as Britain is certain to increase in the wake of the Benghazi attack. Only two days after the storming of Qadhafi's compound in Tripoli last August, Hillary Clinton called on the National Transitional Council to take “a firm stand against violent extremists”.

The Benghazi killing, the ICG now says, must serve as “wakeup call” for Shaghour and colleagues. “There is much to celebrate in post-Qadhafi Libya but also reason to worry,” the report argues. “The battle between central government and armed groups is not yet won, yet of late the latter have been acting as if they enjoyed the upper hand.

‘‘If steps are not swiftly taken, reversing this trend is only going to get harder — and what has been a relatively good news story could turn depressingly sour. Precipitous moves against the armed groups are likely to fail and backfire. But time is running out, the government is plagued by inertia, and the need for across-the-board reforms of the military and police is more urgent than ever.”

By arrangement with the Guardian