The International Organization for Migration (IOM) on Tuesday called on governments to more closely monitor sex trafficking and lend specialized assistance to the 1.5 million refugees expected to enter the European Union this year, warning of a surge in sexual assault against women being smuggled across the Mediterranean Sea from West Africa.

The IOM reported that tens of thousands of people continue to pour into Europe each day, but the group expressed particular concern for the fate of women, who are increasingly representing a larger percentage of refugees. IOM said last week that 4,371 women and girls from Nigeria have reached Italy since January. Most of them — about 80 percent, according to IOM — were trafficked and became victims of sexual violence.

"Over the past few months we have observed an exponential rise in sea arrivals of African women, mainly from Nigeria," IOM's Federico Soda said in a statement.

About 710,000 people, most fleeing violence in Iraq, Syria and Eritrea, have crossed into the EU this year, according to the EU border agency Frontex. About 3,000 people have died during the attempt.

Roughly 13 percent of refugees traveling toward Europe are women, according to the United Nations. Of those, some 4,200 are estimated to be pregnant and another 1,400 "at risk of sexual violence."

But with the prospect of more women and girls arriving, governments and aid groups need to adapt to the needs of the changing demographic, the IOM said. The group called on Italy to open more reception centers for women and to spend more resources against sex trafficking.

Viriri added authorities should also be more attuned to the needs of other vulnerable refugees such as unaccompanied minors and disabled people making their way to Europe.

“We do need to look more at the kind of specialist support that’s needed,” said Itayi Viriri, an IOM spokesman in Geneva. “We certainly need to find out more to make sure that people who do need extra help are given that help.”

On Sunday, the United Nations echoed those sentiments. The U.N.'s Global Initiative to Fight Human Trafficking called on European authorities to improve screening for trafficking victims and protect more vulnerable refugees.

“It is imperative today to acknowledge that not only specific anti-trafficking policies but all related policies and especially migration policies must be consistent with the priority of preventing and eradicating trafficking and exploitation,” Maria Grazia Giammarinaro, the U.N. Special Rapporteur on trafficking in persons, especially women and children, said in a statement.

With wire services