By Tom Phillips in Rio De Janeiro

The sound of helicopter rotors scything through the dawn air signalled what was coming, long before the ground invasion began.

It was 5am on November 19, 2008 and another police operation was beginning in Dona Marta, a notorious hillside slum in southern Rio de Janeiro.

At his home deep in the shantytown Jose Mario Santos, the president of the local residents' association, awoke with a jolt. "The helicopters were like an alarm clock for the community," he recalled.

Minutes later hundreds of police operatives, wielding automatic rifles and shotguns, began pouring up the network of narrow, sewage-drenched alleys that lead into this hillside warren of nearly 2000 redbrick and timber shacks.

Santos, however, remained calm. Born and raised in the shanty -town, the 48-year-old knew the drill all too well. The police would invade, shoot and then leave, possibly taking with them some prisoners or some drugs or leaving behind some bullet-riddled corpses. After that, he thought, things would return to normal.

He was wrong. Instead Dona Marta - a favela perched on the hillside beneath Rio's Christ the Redeemer statue and which was the location for a 1996 Michael Jackson music video shot by Spike Lee - has become the stage for a pioneering security project that authorities hope will help them claw back control of the city's slums from the drug traffickers and will serve as a blueprint for the policing of conflict-struck urban communities across South America. Police operations in Rio's favelas are nothing new. Around 1000 people are gunned down by Rio's police each year, the majority as a result of the war on drugs.

But the use of the counter-insurgency tactics not unlike those being used by coalition forces in Iraq and Afghanistan has never been tried before in Rio; a city that is one of the world's most violent metropolises but is officially at peace.

Instead of being subject to the police's usual sporadic and violent raids, Dona Marta is now under 24-hour police occupation, with officers living among the community, gathering intelligence and pursuing a "hearts and minds" approach that mixes community policing with government-funded infrastructure projects and social work.

In December 2007 local traffickers handed out the gifts to the local children, bankrolling their festive giveaway with the proceeds of their lucrative cocaine markets which were scattered around Dona Marta.

On Christmas Eve 2008, police officers distributed hundreds of toys to the favela's children as part of a propaganda drive intended to convince residents that life is better under police occupation than under the regime of the traffickers, who have now fled.

Authorities shy away from comparisons with the tactics of British or US troops, who tried to improve community relations in places such as Basra by swapping bulletproof helmets for berets.

Rio's police also play down any influence from the Brazilian forces that have been leading a UN stabilisation' mission in Haiti since 2004. There, Brazilian soldiers have sought to conquer the hearts and minds of Haiti's slum dwellers using football and samba as well as rifles and APCs.

But the similarities between these projects are striking and police do describe their experimental project in Dona Marta as a radical change in direction. In Dona Marta, for example, the community police wear a special uniform and armband and are encouraged to patrol the slum's tight backstreets with a pistol rather than their usual FAL-762 rifles.

Policemen can, occasionally, be seen talking to residents, albeit reticently, and the sound of government-funded construction work has now replaced the crackle of gunfire.

"It is a challenge for me as a professional because I've always worked in the conventional way: go in, combat and leave," said Captain Priscilla de Oliveira Azevedo, an angelic-looking 30-year-old policewoman who was handpicked to lead the operation. Now it would be different. "We are installed here."

It was a scorching Wednesday afternoon and Captain Azevedo was staring out over the slum from a viewpoint high in the favela. Next to her stood a former crèche that police have painted blue and turned into their main HQ in the slum. In Haiti, Brazilian troops call such buildings their Pontos Fortes' or strong holds'. In Dona Marta the building is known simply as a community policing post.

Smiling, Captain Azevedo motioned downwards, towards a tatty bar in a square near the top of the favela.

"Before our occupation - right over there, where those people are sat, was one of the places the traffickers installed themselves," she boasted.

Next to the bar dozens of screaming children scurried around an astro-turf football pitch, recently baptized with a kick-about between Rio's governor Sergio Cabral and its newly elected mayor, Eduardo Paes.

Captain Azevedo, who became famous in 2007 when she was kidnapped by drug traffickers and managed to escape, described the Dona Marta occupation as a "laboratory" for the experimental policing of Rio's notorious slums. The initiative is expected to be rolled out across several other favelas, starting with Batan, a place until recently controlled by paramilitary vigilantes who kidnapped and tortured a group of Brazilian journalists in 2008, and Cidade de Deus or City of God which became famous after Fernando Meirelles' 2002 blockbuster film.

Dona Marta's residents have given their new neighbours a mixed reaction.

Some have welcomed the exit of the local drug lord and his men - teenage gangsters from the Red Command gang who used to prowl Dona Marta's streets with AK-47s and hand grenades. Since the traffickers were evicted a gentle trickle of tourists have started visiting the slum, which boasts stunning panoramic views over Rio's Sugar Loaf Mountain and the Guanabara Bay. Many residents say they have benefited from this.

Others are less enamored, doubting that the police will stay in the favela for long. Paulo Roberto Soares, a 48-year-old odd-job man, said he would not oppose the community police.

"As long as they don't mess with the residents and the workers that's fine It's their job," said Mr Soares, who intends to reopen his bar in a part of the favela known as Arena, which until recently was a hang-out for the traffickers. He said he hoped tourists would come to his bar to enjoy a cold beer and its view over Copacabana beach.

"The police have to respect us because we are human beings. But if they start threatening us" His voice tailed off.

"I don't like it," said Ezequiel Liberato, a 14-year-old resident of the slum who said his uncle had been a drug trafficker who was killed by police several years ago. "Everybody is giving interviews saying things have got better but they are lying. It hasn't improved at all."

Liberato said the only real benefit had been an asphalt road built by the police to access their hilltop HQ. The local kids now had a place to skateboard, he said.

Some complain of heavy-handed policing, accusing the fresh-faced community cops, many of them just out of police academy, of aggressive searches and even violence.

"Outside they are saying that this is community policing, that they say good morning, good afternoon and good evening. But here inside the slum we are seeing that it isn't like this," said Mr Santos, the community leader, pointing out that funk parties and bars had been closed down by the occupying force.

"If you ask the residents here what is better - the government or the parallel power - I bet you the huge majority will say the parallel power until they get used to the new reality."

Human rights activists have also given the community policing' scheme a frosty reception.

"We are very skeptical," said Mauricio Campos, an activist from the Network of Communities against Violence. "None of this changes the root problems: police corruption and organised crime involving top members of society."

Authorities say Dona Marta will be different. Since last year a series of major infrastructure projects have been underway here, including the construction of a cable car linking the bottom and top of the slum and of hundreds of new houses for the area's poorest residents, people who until recently lived in wooden shacks. Rio's governor said that more than R$40m (£12m) will be spent rebuilding the area.

But many doubts remain; particularly about if the police will stay in Dona Marta and whether it would be possible to implement such a project in a larger slum. Dona Marta is relatively small, with around 7500 residents. Several of Rio's slums are home to in excess of 150,000 people and are controlled by gangs will hundreds of rifle-carrying foot soldiers. Dona Marta was controlled by 50-60 drug traffickers, police say.

"It is possible to occupy bigger slum. But it needs time for planning," said Captain Azevedo, a friendly police chief who the local press have dubbed the Mother of Dona Marta'.

"It is a long-term project. There were 73 years of abandonment here in Dona Marta The mentality that trafficking helps and you have to support it is passed from father to son. But I believe that things will get easier," she said.

Others believe it is only a matter of time before traffickers try to seize their turf back from police. Several residents told the Sunday Herald they believed the local traffickers were hiding out in a nearby shantytown called Tabajaras.

Most locals are still coming to terms with their guests, having long ago abandoned hope that the state might come to their rescue. A few meters away from the police HQ a resident, tired of waiting for the government to arrive, sought another kind of protection, plastering a rectangular sticker to his front door. "Only God is all-powerful," it read.