Belgium's Dutch-language VTM Nieuws reported thousands of photos and videos, including some showing them having sex, appeared on Discord, a chat room for video gamers.
The images, some of which carried the full names of the victims, were classed according to region in Belgium.
"VTM provided the Brussels prosecutor's office with all the information gathered during their report on the basis of which an investigation was opened," the office said.
"The suspects publicly distributed photos or videos of naked young women without their consent," it added.
The office said it was looking into charging the suspects with "voyeurism" if and when they identify them. A source in the prosecutor's office told AFP "hundreds" of young women were victimised.
Those found guilty of voyeurism can be sentenced to jail for up to five years if the victim is more than 18 years old and 10 years if the victim is between 16 and 18 years old.
The penalty is 15 years in prison if the victim is under 16. Prosecutors suspected former partners of some of the young women distributed the images in cases of "revenge porn." In other cases, they added, hackers entered the women's Facebook accounts to obtain nude photos they can sell.
VTM journalists reported that some of the more than 5,000 images involved under-age victims.
The prosecutor's office did not rule out charges of distribution of child pornographic images.
Child Focus, an organisation that helps find missing children and fights child sexual abuse, said it will look into the case and encourage the victims, especially those whose names are known, to take legal action.
Until now, no suspect has been identified, the prosecutor's office said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)