The European Union is investigating social media company X over suspected breaches of obligations, partly relating to posts following Hamas' attacks on Israel, its first probe under the Digital Services Act (DSA).
The DSA came into force in November last year and requires very large online platforms and search engines to do more to tackle illegal content and risks to public security.
The probe will focus on countering the dissemination of illegal content in the EU, and the effectiveness of measures taken to combat information manipulation, including the "community notes" system, the Commission said.
Earlier this year X launched its "Community Notes" feature, which allows users to comment on posts to flag false or misleading content, in effect crowd-sourcing fact checking to users rather than a dedicated team of fact checkers.
The probe will also examine different aspects of the company's business including the data access which X provides to researchers.
Social media researchers have canceled, suspended or changed more than 100 studies about X, formerly Twitter, as a result of actions taken by its owner Elon Musk that limit access to the platform, Reuters reported last month.
"The step that we are taking today does not find X guilty of an infringement, or conclude that X has actually infringed the DSA but merely states that we have significant ground to investigate these areas in detail," a senior EU official said.
X remains committed to complying with the DSA and is cooperating with the regulatory process, it said in a statement on Monday.
"It is important that this process remains free of political influence and follows the law," it said.
Musk, in a post on X, asked EU industry chief Thierry Breton if similar action was being taken against other social media platforms.
"Because if you have those issues with this platform, and none are perfect, the others are much worse," he added.
Following Hamas' attacks on Israel on Oct. 7, X, formerly known as Twitter, and other social media companies were flooded with fake images and misleading information.
Breton sent letters to X, Meta (META.O), TikTok and Alphabet (GOOGL.O) reminding them of their obligations under the DSA to tackle harmful and illegal content.
The platforms responded by highlighting steps they have taken to stop disinformation on their platforms, but Musk challenged Breton over the disinformation charge.
X is part of a group of large tech companies facing increased scrutiny under the DSA. Only X has so far received a formal request for information under the DSA.
Some Italian politicians defended Musk and criticised the EU Commission. Musk had spent the weekend in Rome, speaking at a right-wing political gathering organised by Italian Prime Minister Giorgia Meloni's party.
"@elonmusk is right: 'freedom of speech only makes sense if it allows people you don't like to say the things you don't like'," tweeted Italy's deputy PM and far-right leader Matteo Salvini.
The Commission said it will now carry out an in-depth investigation by sending additional requests for information and conducting interviews and inspections, it said.
It will also review measures taken by X to increase transparency and Blue check subscriptions, it said.
The Commission said a preliminary investigation conducted so far has included an analysis of a report submitted by X in September, X's transparency report published in November, and X's replies to a formal request for information about illegal content in connection to Hamas' attacks on Israel.
The DSA imposes new rules on content moderation, user privacy and transparency. Any firm found in breach faces a fine worth up to 6% of its global turnover.
