In the narrow streets of the Palestinian refugee camp in Jenin and the scruffy villages beyond, masked special forces bundle suspects into civilian cars with grim regularity, whisking them away to faraway Jericho prison.

The near-nightly crackle of gunfire, sometimes from drive-by shootings against police stations, has accompanied a crime wave in the northern city of Jenin, once a hub of militants and suicide attackers who struck into nearby Israel.

The Palestinian Authority (PA), in partial control of the Israeli-occupied West Bank, has responded aggressively, if belatedly and, critics say, with scant regard for due process.

The crackdown, led by elite presidential guards and the counter-terrorism unit, is seen as a determined bid by the Western-backed PA to regain control of the impoverished area and smash local networks that challenge its power.

Its forces are swooping not only on local strongmen and rival gangsters who smuggle drugs and rob, but also on rogue security officers suspected of arming and directing them.

The PA, with the Fatah party at its core, has advanced its monopoly on force in the West Bank after years of purges and scraps with rival factions - a process it is now looking to complete among its own ranks and erstwhile allies.

Despite lacking a formal state or a mandate from the ballot box, the PA considers the security sweep in Jenin as a template for cementing its authority throughout the West Bank.

"This is an ongoing security effort and not a campaign with a start and finish. It will encompass every district so that citizens can live in safety and security," Palestinian Prime Minister Salam Fayyad told Reuters.

"What's going on now is patching the gaps (in the security establishment) through a focused security effort," he said. "We're not talking about a limited operation here."

After months of unrest, the PA finally swung into action in May when the governor of Jenin died of an apparent heart attack after a midnight fire-fight outside his house, which many locals attributed to rivalries within the restive security forces.

For most of its 45 years under Israeli occupation, Jenin has been dominated by an anarchic patchwork of grassroots political groups and armed factions with shadowy local bosses.

PALESTINIAN "GUANTANAMO"

The depth of the city's crime problem was exposed last year by the murder of Israeli-Palestinian actor Juliano Mer-Khamis, who had set up a youth theatre in Jenin. Armed gangs of smugglers and profiteers began to feud more and more openly.

Officials acknowledge the involvement of some corrupt senior officers in the criminal networks, saying the Jenin governor's death shocked the government into purging those elements and tackling the security challenge more systematically.

The government had some awareness of what the tainted security officials were up to, but their party affiliations shielded them from disciplinary action, the officials say.

"During recent times in Jenin there was some laxity, and in military work, laxity can lead to chaos," said a security official, speaking on condition of anonymity.

"This is the challenge to the Palestinian Authority: whether it is to enforce its power and decisions, or let things fall out of its hands."

But families of some detainees criticise the PA for holding their kin without charge or trial and cracking down on Palestinians instead of combating Israeli occupiers.

One prominent figure caught up in the sweep is Zakaria Zubeidi, known for his role in a 2000-2005 Palestinian Intifada, or uprising, against occupation. He led the Fatah-linked al-Aqsa Martyrs Brigades, a militant group dormant in the West Bank since the party disavowed armed conflict with Israel.

Once a political power broker in Jenin and an ally of the PA, Zubeidi's fall from grace has been dramatic. Arrested two weeks ago, he awaits charges for unspecified crimes in dusty Jericho prison, the PA's central jail in the Jordan Valley.

"Jericho has become like Guantanamo," groaned Zakaria's brother Abed, referring to the U.S. detention centre in Cuba where suspected al Qaeda members sometimes languish for years.

"The idea of being sent there is being used to terrify us," he said, glancing suspiciously out of his car repair shop.

"People come in here all the time with their car windows smashed by (Israeli) settlers. The Authority doesn't defend its people from the attacks, but directs its policy of force at us."

The new governor of Jenin, Talal Dweikat, ensconced in a headquarters bristling with soldiers and shrouded with posters of his late predecessor, argued that the PA's efforts would ultimately advance the cause of independence.

"It will show the world that we as the Palestinian Authority are capable of directing the institutions of the Palestinian state we seek," Dweikat said.