The European Union on Friday (Nov 10) announced probes into tech giant Meta as well as social media firm Snap seeking details on measures taken by the companies to put a pause on the circulation of illegal content online.
The tech firms have been asked to elaborate on the ways they will safeguard children from harmful content on the internet, the European Commission said.
It had sent formal requests for information to the companies and they had until December 1 to respond.
This comes a day after similar probes were opened into YouTube and TikTok to check the measures in place to protect minors from illicit content.
These investigations are in the initial stage under the EU's Digital Services Act, which came into force in August and do not themselves comprise a declaration of legal infractions or a step towards penalising the firms.
Last month, the EU had launched probes into TikTok, X and Meta over the dissemination of disinformation amid an upsurge of violence between Israel and the Palestinian militant group Hamas.
"I would ask you to be very vigilant to ensure strict compliance with the DSA rules on terms of service, on the requirement of timely, diligent and objective action following notices of illegal content in the EU, and on the need for proportionate and effective mitigation measures," the European Union's industry chief Thierry Bretontold Meta CEO Mark Zuckerberg in a letter.
EU's top tech regulatorhad also warned Elon Musk that his social media platform X was spreading "illegal content and disinformation".
"Following the terrorist attacks carried out by Hamas against Israel, we have indications that your platform is being used to disseminate illegal content and disinformation in the EU," he wrote in the letter.
(With inputs from agencies)