The firm's CEO Linda Yaccarino wrote that the platform, formerly Twitter, had "taken action to remove or label tens of thousands of pieces of content" and removed hundreds of accounts linked to Gaza militant group Hamas, which attacked Israel on Saturday prompting a brazen siege on the Palestinian enclave.

She addressed the letter, dated Wednesday, to EU industry commissioner and self-styled "digital enforcer" Thierry Breton, who had traded barbs with Musk on social media after accusing the platform of allowing violent content to circulate.

Breton has sent similar letters of alarm to Mark Zuckerberg, boss of Facebook parent Meta, and on Thursday to TikTok and its CEO Shou Zi Chew.

In each case, Breton gave the platforms 24 hours to get back to him with details of what they are doing to crack down on what they called "illegal content and disinformation" reportedly circulating in posts.

Breton stressed that the large online platforms are now subject to the EU's Digital Services Act (DSA), legislation that came in two months ago that requires them to crack down on content deemed illegal under EU law or laws of individual EU countries.

Violations of the DSA can be met with mandatory remedial measures to halt such content, or fines that could go up to six percent of a company's global turnover, or potentially even steps to ban the platform from Europe.

Breton posted copies of each of his letters to his accounts on X and on an X rival called Bluesky.

X is especially fixed in Brussels' crosshairs because Musk, who bought Twitter for $44 billion last year, has gutted its staff, including content moderators, in a bid to save money.

Young TikTok users at risk
 

Yaccarino's response letter to Breton, reposted by the CEO on her X account, said the firm had taken down posts that involved "violent speech, manipulated media and graphic media".

She said that more than 700 notes were added to posts in the first four days after the violence erupted in Israel, and they were seen tens of millions of times.

The European Commission told AFP it had received the letter and was deciding its next steps.

In his letter to TikTok, Breton stressed that its users, who are mainly young, were especially vulnerable to fake and manipulated information.

"Given that your platform is extensively used by children and teenagers, you have a particular obligation to protect them from violent content," Breton said.

To Zuckerberg, Breton noted that Meta had made some efforts at content moderation but urged it to be "vigilant" about meeting DSA requirements in light of the current Israel-Hamas conflict.

A Meta spokesperson said in reply the company had quickly set up monitoring teams with experts speaking Hebrew and Arabic, was working with fact checkers to curb disinformation, and that "we'll continue this work as this conflict unfolds".

AFP fact-checkers have found several posts on X, Facebook and TikTok promoting a fake White House document allocating $8 billion in military assistance to Israel.

And several platforms have had users passing off material from other conflicts, or even from video games, as footage from Israel or Gaza.

The EU recently rated X as the worst of any major platform for illegal online content based on a pilot analysis, and Musk has pulled out of a voluntary EU code of practice on battling disinformation.

*This story was edited by Ahram Online