Sickening allegations of refugee women and children being forced to engage in sex to survive have been reported by the United Nations.

The United National High Commission for Refugees said it had received credible reports of sexual abuse of women and children asylum seekers across Europe.

A mass migration has hit Europe as millions of Syrians, Afghanis and Iraqis flee devastating civil war and political unrest.

• Not all refugees are Syrian
• Govt begins assessing refugees
• Baby’s body washes up in Greece

The commission said poor refugees were being forced to sleep with people smugglers in order to keep moving through Europe, although it is not yet known how prolific the problem is.

Women and children travelling alone are particularly vulnerable. Photo: Getty

Women and children travelling alone and forced to sleep outdoors were particularly vulnerable, the commission warned.

“From testimony and reports we have received there have been instances of children engaging in survival sex to pay smugglers to continue their journey, either because they have run out money, or because they have been robbed,” UNHCR said in a statement.

Commission spokesperson Melissa Fleming told reporters the abuse was widespread, but likely highly concentrated in the Balkans, reported News.com.au.

“You’re seeing these desperate cases of parents sending their children ahead at really young ages,” she said.

“We are calling on all concerned national authorities in Europe to take measures to ensure the protection of women and girls and children.”

The displacement of Syrian people since the outbreak of civil war in 2011 is the worst humanitarian crisis of our time.

It is estimated half of Syria’s population is either displaced or deceased since the war began.

Among the scramble to relocate the displaced, Germany has pledged to take 800,000 asylum seekers this year, while Australia has promised a one-off intake of 12,000.