Children as young as age seven are being targeted online by criminals involved in digital blackmail and so-called "sextortion", a new report from Europol claims.
The number of incidents of this type of online coercion and extortion has exploded in recent years, the study says.
According to the European police force, those behind the crime most often have a sexual interest in children and use the extortion to procure sexual photos or video of the child.
They also can use it to manipulate children into taking part in an offline sexual encounter, Europol says.
Some of the criminals also target young people in order to gain financially, the report states.
Girl victims are most often blackmailed for sexually explicit material, while boys are targeted more than girls for financial gain.
Criminals have also begun to demand that victims include other children, including peers and siblings, in the material.
Europol says embarrassment means the problem goes largely under-reported and has resulted in victims self-harming and dying by suicide.
Police across Europe, supported by Europol, have launched a campaign to advise those who could or who have fallen victim to the crime.
They are also trying to raise awareness of and strengthen support mechanisms.
Europol says if a victim shares a sexual image with a perpetrator who then tries to blackmail them into sharing more, they should not.
They also should not pay the perpetrator anything.
Instead, Europol recommends that the victim looks for help, preserves evidence, doesn't delete anything, stops communicating with the perpetrator and blocks them and reports the incident to police.
More information is available on the #SayNo campaign page on the Europol website.