By Tom Miles

GENEVA, June 16 (Reuters) - Rich countries must learn the lessons of the war on drugs and the U.S. prohibition of alcohol in the 1920s and realise that trying to stop migrants from moving is just making the problem worse, an independent U.N. expert said on Tuesday.

The European Union is struggling with the question of what to do about hundreds of thousands of migrants flocking to its shores across the Mediterranean, often dying in the attempt.

"By erecting prohibitions, we have actually created a market for smugglers," François Crépeau, the U.N. special rapporteur on the human rights of migrants, told a news conference in Geneva.

"Prohibition breeds underground markets."

At least 219,000 migrants arrived in Europe in 2014 after crossing the Mediterranean - a figure Crépeau said was equivalent to just 0.0004 percent of the European population. But a further 3,500 died at sea and many more may be perishing in the Sahara as they try to reach the Libyan coast.

"It could be that there are 3,000 deaths in the desert before getting to Libya or it could be 10 times as high. No one knows," said Crépeau.

The International Organization for Migration (IMO) said 30 migrants had been found dead in the Sahara in Niger on Monday.

"I'm quite sure that in governme

"If we started shooting people at the border and killing thousands, that might deter."

nts, some policy advisers think and say that the more people die, the more there is deterrence," Crépeau said. But migrants would always have hope of getting through, he added.

 

By legalising, regulating and taxing migrants, Crépeau said European Union countries could ensure they knew where they were and ensure they complied with their visa conditions, rather than driving them into an undergound economy.

SMUGGLERS

But instead of coming to grips with the issue of migrant mobility, rich countries have pushed frontier controls far from their own borders, for example by forcing airlines to check visas before passengers can board.

"We can manage this instead of it being managed by smugglers and we being all surprised when this happens," he said.

Crépeau has previously suggested that rich countries should take in one million refugees over five years, while economic migrants should be offered visas that incentivise them to stay within the rules while trying to find work.

"People will line up. People will not risk 20,000 euros and the life of their kids if there is a Danish (visa) booth and a Canadian booth and a New Zealand booth," he said. (Editing by Gareth Jones)