As human rights groups warn of a growing “culture of impunity” in Cote d’Ivoire, the United Nations has called on officials to speed up the dismantling of pro-government militia after a UN staffer was briefly detained this week.

On Monday, a group of some 200 militiamen in the western government-run town of Duekoue held the UN employee, demanding money from the government disarmament programme in return for his release, the UN Operation in Cote d'Ivoire (ONUCI) said in a statement on Tuesday.

The incident followed clashes on Friday that pitted pro-government militia holed up in improvised barracks against angry residents and security forces in the Yopougon suburb of Cote d’Ivoire’s main city, Abidjan.

Two members of the Patriot Grouping for Peace (GPP) militia were burned alive and two residents died from knife injuries sustained in the fighting. The clash marked the first time local residents single-handedly attacked a militia camp since the war erupted.

Human rights groups say the recent actions by militia members reflect a serious problem with impunity in Cote d’Ivoire, which has been divided between a government-run north and a rebel-held south since a failed coup triggered a brief civil war in 2002

"There is always the probability that the cycle of violence will repeat itself as long as there is a government in place that seems unwilling or unable to address the fundamental impunity which allows these groups to operate," Dustin Sharp of New York-based Human Rights Watch (HRW) said.

The latest trouble in Yopougon erupted last week when several militia members began looting grocery stores for rice and palm oil. The militia had been stealing construction material, food and cellular phones for months, and the looting spree was the "last straw", according to resident Antoine Kouame, who is unemployed.

"We were tired of it," he said. "We are very happy that they are gone. We can go about our business as usual again."

Nearly 400 GPP militia members had been camping on the abandoned lagoon-side site since police and gendarmes had evicted them from a school they had illegally occupied in a central neighborhood last year.

Members of the GPP are not included in the national disarmament programme (PNDDR) designed to disarm pro-government militia in the south and rebels in the north because they never openly admitted to carrying guns.

In an unrelated incident in July, scores of GPP militia attacked striking maritime police demanding the departure of their general director. Local press reports suggested the head of maritime affairs, who had been accused of embezzlement, had hired the militia to intimidate and harass the strikers.

The GPP is one of several pro-Gbagbo militia groups set up during the first months of fighting in Cote d'Ivoire's brief civil war. It was officially disbanded last year and it is unclear whether its members still receive payments.

A government attempt to disarm another pro-government militia group, the Forces for the Resistance of the Grand West (FLGO) based in the western region, failed earlier this year because too few weapons were handed in.

Analysts say many army officials feel increasingly uncomfortable with the existence of opaquely controlled militia gangs that undermine the authority of the country's security forces.

"The militia were useful when there was actual fighting but the army has been propped up since and doesn't feel it needs them anymore," said a military observer speaking on condition of anonymity.

An Ivorian army spokesman initially denied that security forces were involved in the Yopougon violence, but eyewitnesses said residents received help from the government’s anti-riot brigade and a special crime unit.

However, the GPP militia still receives protection from some high-ranking military officials who arranged temporary lodging at the police and gendarmerie schools in central Abidjan, a government official told IRIN on condition of anonymity.