Facebook has ramped up efforts to combat hate speech in Europe and is now in compliance with voluntary guidelines agreed to last year, the European Commission (EC) said this week, but Twitter and YouTube are still lagging behind.

In a report published Thursday, the EC said tech companies have made “significant progress” in complying with a voluntary “code of conduct” to review the majority of hate speech complaints within 24 hours. Facebook, Twitter, YouTube, and Microsoft signed on to the code of conduct in May 2016. European lawmakers are currently considering legislation that would require tech companies to block videos that contain hate speech or terrorist propaganda, as part of a broader effort to curb illegal speech online. Such proposals have raised concerns from digital rights groups who fear that they could infringe on free speech.

An EC evaluation published in December 2016 found that tech companies were still failing to comply with the code of conduct, noting that just 40 percent of reported material was reviewed within 24 hours, and just 28 percent of flagged content was removed. Six months later, the companies have reviewed 51 percent of reported content within 24 hours, and removal rates increased to 59 percent, according to the report released this week. The EC’s findings were first reported by The New York Times on Wednesday.

"The results of our second evaluation of the code of conduct are encouraging,” EU Justice Commissioner Vĕra Jourová said in a statement Thursday. “The companies are now removing twice as many cases of illegal hate speech and at a faster rate when compared to six months ago. This is an important step in the right direction and shows that a self-regulatory approach can work, if all actors do their part.”

Facebook is the only company that currently complies with the code of conduct, according to the EC. The company reviewed nearly 58 percent of flagged content within 24 hours — up from 50 percent in December — compared to 42.6 percent for YouTube and 39 percent for Twitter. Twitter has accelerated its moderation procedures since December, when the EC found that it reviewed just 23.5 percent of reported content within the 24-hour time frame. But YouTube has seen its rate fall; in December, the Google-owned site reviewed 60.8 percent of flagged content within 24 hours.

The report also highlights “a large disparity” in how social media companies provide feedback to those who report hate speech. According to the EC, Facebook provided feedback in 93.7 percent of reported cases, compared to 32.8 percent for Twitter and 20.7 percent for YouTube. Xenophobic and anti-Muslim content were the most commonly reported, accounting for a combined 34 percent of notifications, followed by content targeting ethnic origin (15.8 percent).

“Over the past six months, we've introduced a host of new tools and features to improve Twitter for everyone,” Karen White, Twitter's head of public policy for Europe, said in a statement to Reuters. “We’ve also improved the in-app reporting process for our users and we continue to review and iterate on our policies and their enforcement. Our work will never be 'done.'"

Juniper Downs, head of public policy at YouTube, tells Reuters that the company has “learned a lot from” the EC’s code of conduct “and will continue to invest heavily in people and systems to address these issues.”

Tech companies have been facing increased pressure to curb hate speech across Europe. Germany is currently considering a law that would impose fines of up to €50 million ($56.1 million) on companies that fail to quickly remove hateful content, while UK Prime Minister Theresa May expressed support for a similar measure following the Manchester terrorist attack last month.