Migrants are unfairly blamed for unemployment and social problems in tough economic times, the International Organisation for Migration said Tuesday.

Describing migration as "one of the most misunderstood issues of our time," the body called in a new report for a shift in attitudes, saying negative views of migration arise in particular during economic recession and spikes in joblessness, it said.

"It is all too evident that migration is often the catch-all issue that masks public fears and uncertainties relating to unemployment, housing and social cohesion in host countries," said IOM director general William Lacy Swing.

The report titled "Communicating Effectively about Migration" said anti-migrant sentiments were resurfacing in many parts of the world.

"Harmful stereotypes, discrimination and even xenophobia have reappeared in societies of destination, resulting in controversy on the value of multi-culturalism," said the IOM, which is marking its 60th anniversary this year.

People also tend to overestimate the size of the migrant populations in their countries, often by as much as 300 percent, it said.

In a poll carried out for the report, Italians questioned on the issue suggested 25 percent were migrants when the true figure last year was closer to seven percent, the IOM said.

"Accurately informing the wider public about migration may be the single most important policy tool in all societies faced with increasing diversity," Swing said.

The IOM, which promotes international cooperation on migration and employs 7,300 staff in more than 100 countries, now boasts 146 members.

On Monday it welcomed 14 new states as members, including Ethiopia, South Sudan and the Holy See.