With the implementation of the U.K.’s Online Safety Act (OSA) provisions for addressing illicit content now in effect as of Monday, the internet regulator Ofcom has initiated a new enforcement initiative targeting online storage and file-sharing services.

According to Ofcom, its findings indicate that file-sharing and file-storage services are particularly vulnerable to exploitation for the dissemination of image-based child sexual abuse material (CSAM). The enforcement program will evaluate the safety measures these services have implemented to prevent the spread of CSAM on their platforms.

Ofcom has notified several of these services, though it has not publicly disclosed their identities. The regulator has informed them that formal requests for information regarding their existing and planned measures to combat CSAM will be forthcoming, and they will be required to submit risk assessments for illegal harm.

Non-compliance with the OSA may result in substantial penalties, potentially reaching up to 10% of the company’s global annual turnover.