French police on Wednesday expelled around 550 people from makeshift camps in the northern port of Calais after a scabies outbreak, drawing criticism from rights groups over the treatment of migrants hoping to reach Britain.

Some 200 policemen were deployed to evict the occupants from the camps which were then bulldozed.

French officials defended the action on public health grounds. But it was slammed as "reckless and ill-considered" by charity group Doctors of the World.

"Evictions will not reduce the number of migrants on the streets of Calais, but will disperse them, making them harder to assist, document or trace. This will further impinge on their basic right to healthcare and shelter," said Leigh Daynes, the head of the NGO's British section.

He said it could also cause "migrants to attempt higher risk strategies for getting to the UK -- leading to more unnecessary deaths."

France's Interior Minister Bernard Cazeneuve said the eviction had been a "humane" operation.

"When there are Eritreans and Syrians on our territory living in improper sanitary conditions we must put an end to their difficulties," Cazeneuve said.

Charity workers said the occupants of the camps had been left with nowhere to go.

"The people are on edge and are looking for the place where they will feel the safest," Cecile Bossy of Doctors of the World told AFP at the scene.

The authorities said the expulsion was aimed at stopping an outbreak of scabies in the camps, which had no running water or sanitation.

The people in the camps lived in makeshift shelters and tents constructed essentially with bits of wood and plastic sheeting.

Some of the migrants put up improvised barricades with rubbish skips but the operation passed off without any violence.

One Afghan cried out in broken English: "Where is human rights? No human rights. We risked our lives and got here. No disease, we want to live here with humanity."

- Security threat -

Denis Robin, the prefect of the Pas-de-Calais region, said the highly contagious nature of scabies, a relatively minor type of skin infection, made the sweep necessary.

"It's a public health issue. All the studies indicated that there was a scabies epidemic. These camps are very big and they are located right in the heart of Calais," he said.

Robin also said the camps had grown to the point that they posed a security threat for local residents.

The migrants were asked to board buses and were taken to meet French immigration officials to examine their individual cases, after having taken showers and undergone treatment for scabies.

Immigration officials issued an appeal to local residents to take in the migrants on a temporary basis until alternative arrangements could be made, but rights activists said this was not enough.

"What will these people do now? Live on the streets, roam around," said Vincent Deconinck from the Secours Catholique charity.

"The situation has been like this for 10 years now and it's not by making their lives worse that one will make them disappear," he said.

Illegal camps of migrants seeking to cross the Channel have sprung up in the Calais area since the French authorities closed down the infamous Sangatte immigrant detention centre in 2002.

Between 40 and 50 people are caught every night trying to cross the Channel illegally, according to Calais authorities.

Many of the migrants living in Calais and trying to enter Britain illegally think they will have a better future there than in France and take huge risks to get there.