NOSY BE, Madagascar, (AFP) - The police in Madagascar made five more arrests on Saturday on the tourist island of Nosy Be after a raging mob lynched and burned two Europeans and a local man they accused of killing a boy.

The authorities on the idyllic Indian Ocean island have now arrested 19 people in all, having taken 14 others into custody on Friday and vowing to arrest anyone involved in the lynchings and riots as well as anyone who filmed or photographed the killings.

Heavy security forces deployed on the island on Saturday, with officers on foot and in pick-ups patrolling Hell-Ville, its tiny capital, after a tense night during which the government imposed a curfew from 9pm to 4am.

The gory rampage was sparked by the death of an eight-year-old local boy, whose body was found on the popular Ambatoloaka beach a week after he went missing.

"His body was wet when it was found. So it's possible he drowned," Mr Vincent Laza, a neighbourhood leader on the island, told AFP, adding that the boy's genitals were missing and his intestines were exposed.

By Wednesday reports had begun to circulate that the boy had been kidnapped, causing a mob to storm the gendarme station - convinced that one of the boy's killers was being held there.

Officers opened fire and two people were killed.

Amid rumours that foreigners were involved, a mob of hundreds got their hands on a Frenchman and a Franco-Italian on Thursday and torched them on Ambatoloaka, a popular beach ringed by bars and hotels.

Pictures and video images taken by residents captured the moment when one of the bodies was burned in front of about 100 people, including a man who was both armed and wearing a uniform.

Afterwards a pile of ash, wood, a torso and a pair of charred legs were the only recognisable signs of the orgy of violence.

A local man who was the boy's uncle was later also killed and burned.

The boy's father Luciano Anjara told AFP his son Chaino had disappeared a week ago.

"He went to the mosque all day Friday, then on Friday evening he left accompanied by his friends," he said.

"According to his friends he began to run home at (the suburb of) Dar-es-Salam, that child loved to run. Between the market and our house, he was gone."

With its white sandy beaches and turquoise waters, Noisy Be is Madagascar's main tourist magnet, but the island also has a seedy underbelly and is known for sex tourism.

Mob justice is common on the vast island nation off the south-eastern African coast, which the authorities struggle to police effectively.

Locals insisted the lynchings would not affect tourism.

"We are targeting the culprits. It's public justice - we just kill them, and if you refuse to kill them we kill you because you're an accomplice," said Jacob, a Hell-Ville native.

"We've got nothing against foreigners. You can come visit and there won't be a problem," he told AFP.

One resident claimed the crowd had made sure the Europeans were guilty.

"They spoke for a long time until the morning hours, and then the foreigners confessed they had killed the child. We have it on video," said Lala, who lives in the Dar-es-Salam suburb where the local man was killed.

In an audio recording, one of the victims was however heard declaring his innocence as the crowd accused him of being a paedophile and killer.

"I have not hidden anything, madame, I am innocent, it's a plot against me," he was heard telling a woman, who responded: "You tell us the truth, otherwise we will lynch you in front of everyone."

District head Malaza Ramanamahafahy named the Frenchman as Sebastien Judalet and said his passport indicated he was a frequent visitor to Madagascar.

Mr Ramanamahafahy added that the Franco-Italian, whom he named as Roberto Gianfala, had an expired Madagascan visa.

Both France and Italy confirmed the deaths and have urged their citizens on Nosy Be to remain vigilant and stay indoors at night.

Six French nationals were evacuated to Madagascar's capital Antananarivo, local police said Saturday.

About 700 French people live on the island of 40,000 residents, with around 100 French tourists currently visiting.