GENEVA (Reuters) - Migrant children making the perilous journey to Europe to escape war and poverty face possible beatings, rape and forced labor in addition to risk of drowning in the Mediterranean, the United Nations Children’s Fund (UNICEF) said on Tuesday.

Minors account for a growing percentage of migrants and refugees, particularly those trying to reach Italy by sea from Libya, it said in a report, “Danger Every Step of the Way”.

Of the roughly 206,200 people who arrived in Europe by sea this year to June 4, one in three was a child, it said, citing figures from the U.N. refugee agency.

“Every step of the journey is fraught with danger, all the more so for the nearly one in four children traveling without a parent or guardian,” UNICEF said.

That ratio was far higher on boats from Libya, where more than nine out of ten children were unaccompanied. UNICEF said there were almost 235,000 migrants and refugees in Libya and 956,000 in the Sahel, many or most hoping to go to Europe.

UNICEF said that there was “strong evidence that criminal human trafficking networks were targeting the most vulnerable, in particular women and children.

“Italian social workers claim that both boys and girls are sexually assaulted and forced into prostitution while in Libya, and that some of the girls were pregnant when they arrived in Italy, having been raped,” it said.

The U.N. refugee agency has said the flow of people from Turkey to Greece has slowed hugely but dealing with migrants now stranded along the route remains a huge challenge. [nL8N1954FE]

UNICEF said many children had fallen between the cracks of overstretched asylum systems and their cases should be a priority.

“All too often children are held behind bars - in detention facilities or in police custody - because of a lack of space in child protection centers and limited capacity for identifying alternative solutions,” it said.

U.N. human rights chief Zeid Ra’ad Al Hussein has decried a “worrying rise” in detentions of migrants in Greece and Italy and urged authorities to find alternatives to confining children while asylum requests are processed. [L8N1951GW]

Authorities in some countries take up to two years to evaluate a child’s request for asylum, and processes to reunify families can be equally slow, UNICEF said.

Once in Europe, migrants and refugees are often housed in sports halls, former military barracks or other temporary shelters, sometimes without access to schooling and psychological support, it said.

Some have faced xenophobic attacks, hate speech and stigmatization, it said, citing 45 arson attacks on refugee shelters in Germany during the first half of this year.