Twenty-four hours after Libya's police force opened its doors for the thousands of militia members to join its ranks, only 100 had signed up, signalling the long road the government faces to bring the unruly militias to heel.

The militias, which fought to unseat former leader Muammar Gaddafi, are now the biggest threat to stability in Libya, clashing regularly with each other in violent turf wars and undermining the authority of the country's new rulers.

The interim government, the National Transitional Council (NTC), wants to amalgamate the militias into the police force and army. The NTC's chief said this month that if they do not comply, the country risks being dragged into a civil war.

But on the evidence of the trickle of people signing up at the Interior Ministry's main recruitment centre in a Tripoli compound, most militia members are still reluctant.

An official at the site said that between Saturday morning and Sunday morning -- part of the working week in Libya -- they had signed up 100 people.

There are no reliable figures for the number of fighters in Libya's militia units, but they could number in the hundreds of thousands.

Those that did turn up to seek jobs in the new police force were not from the heavily-armed and well-organised militias from outside Tripoli which pose the biggest headache for the NTC.

Instead, the prospective new recruits were from smaller militias which in any case did not have the resources to challenge for power. Some recruits said they were there because their units had not paid them.

Sunday morning, about a dozen young men, mostly dressed in civilian clothes and holding their green identity cards, stood outside the registration office, located in a busy Tripoli district near Nasser University.

They had filled out the job application to join the police and were waiting to be called so that they could sign an employment contract.

Once the contract is approved, each new recruit would be paid 600 dinars a month, an interior ministry official, who asked not to be named, told Reuters. That is about $450, a modest salary by Libyan standards but enough to live on.

An official said they would be hired initially for six months, after which their contracts will be reviewed.

One of the would-be police officers was Adel Muftah, 25, who joined a militia unit after the fall of Tripoli in August.

I've come here because this is a legitimate force, Muftah said, wearing the khaki military uniform favoured by many militia fighters. I haven't been paid for two months by the militia.

INCENTIVES PROMISED

The clerks whose job it was to register the potential recruits would not comment on whether the numbers who had signed up were in line with expectations.

The clerks said they had been given no deadline to stop accepting applications, though government officials had previously said they wanted to complete the process within a month.

Salah Mohammed Makhlouf, commander of a Tripoli-based militia, said he had asked his fighters to sign up for the interior ministry jobs.

He said he was promised by government officials that some of his fighters would be trained in Jordan, Qatar, Sudan and the United Arab Emirates.

But the most powerful militias, and the ones most reluctant to hand over to the central government, are those affiliated to cities such as Zintan and Misrata.

They played a major role in the fight to oust Gaddafi, and do not want to disband until they are sure they will be given a stake in the new Libya that matches their contribution to the revolution.

Mokhtar al-Akhdar commands a 1,200-strong force drawn mainly from Zintan, which controls Tripoli airport. His men have fought gunbattles with rival militias.

He said he was talking to the government about transferring control of the airport to the authorities.

But when he was asked last week to give a timeline, he said he needed to see a strong government force in place first before he could surrender control.

We are throwing the ball to the ministries of defense and interior. We will see what they do, Akhdar told Reuters. We are patriotic and our nation is what we care about the most.

(Writing by Mahmoud Habboush; Editing by Christian Lowe and Peter Graff)