A number of known British pedophiles have been told to leave Poland after British authorities discovered they traveled there to target Ukrainian children in refugee camps, the National Crime Agency said on Thursday.

The ten men were interviewed by Polish immigration authorities before being sent home, the National Crime Agency (NCA) told the Independent. According to an NCA spokesperson, the men failed to declare their convictions upon arriving in Poland, which they were required to do by law. 

The convicted predators reportedly claimed they were offering "humanitarian assistance" to refugees fleeing the conflict in Ukraine, of which at least 5,000 in Poland are unaccompanied children, the spokesperson continued. 

"For us, it's about making partners aware that these convicted child sex offenders are on their turf, for obvious reasons," the NCA official said. "Making sure [the children are] safe is absolutely paramount."

It is unclear whether the pedophiles came in contact with any Ukrainian children before they were deported.

In addition to child refugees, women fleeing Ukraine have also been threatened by abusers. Ukrainian authorities arrested the leader of a criminal gang earlier this month, claiming that his group offered jobs abroad to women looking to leave the country, only to traffic them into prostitution in Turkey.