The IOM said nearly half of 4,600 migrants aged 15-24 reported physical violence during their journeys to Europe, particularly in Libya. (EPA Images pic)

GENEVA: The majority of migrant children who reached Europe last year were travelling alone, UN agencies said Wednesday, warning about the abuse and violence they face en route.

More than 20,000 of the 31,100 children who reached Europe along migration routes last year arrived without a parent or guardian, the agencies said in a statement.

"This report shows how exposed they are to violence and exploitation when safe pathways are limited, and they have to rely on smugglers," said Amy Pope, director general of the International Organization for Migration. "No child should have to face these risks alone."