Ballots at a polling station Greece during the European elections | Sakis Mitrolidis/AFP via Getty Images Russian groups targeted EU election with fake news, says European Commission Analysis finds ‘continued and sustained disinformation activity.’

Russian groups carried out a widespread disinformation campaign aimed at influencing the European Parliament election, according to an analysis by the European Commission and the European Union's diplomatic service.

These digital tactics were aimed at undermining the EU's democratic legitimacy and used hot-button topics to sow public anger, based on evidence collected by Brussels-based institutions in a report released Friday.

"The evidence collected revealed a continued and sustained disinformation activity by Russian sources aiming to suppress turnout and influence voter preferences," the analysis said. "These covered a broad range of topics, ranging from challenging the Union’s democratic legitimacy to exploiting divisive public debates on issues such as of migration and sovereignty."

The attribution to “Russian sources” is exceptional, as the EU is generally cautious to point fingers at foreign countries when commenting publicly on cybersecurity attacks.

But lately the Kremlin has come under increased attention for attempted digital assaults on international institutions in The Hague late last year, and suspicion has grown among Western officials that Russia was behind a hack that targeted the EU’s diplomatic mission in Moscow — an incident that became public last week.

"The disinformation campaigns were smart and subtle to focus on issues that mattered to the target audiences" — Chloe Colliver, Institute of Strategic Dialogue

As part of widespread "fake news" around the election, domestic political groups and politicians also borrowed heavily from tactics initially used by Russia-backed groups, including efforts to sway discussion on social media, the report said. The goal, according to the EU analysis, was to promote extreme views and polarize national political debates ahead of last month's vote.

The analysis said it is too soon to conclude whether the online campaigns had influenced turnout or voters' choice of party.

"Given the increasingly sophisticated nature of disinformation activities, and the difficulties of independent researchers to access relevant data from the platforms, a conclusive assessment of the scope and impact of disinformation campaigns will take time and require a concerted effort by civil society, academia, public actors and online platforms," the report said.

The report matches similar research by other disinformation experts that saw domestic and Russian-backed groups borrow heavily from each other — both in terms of tactics and digital content — in their efforts to sway last month's vote.

Because disinformation groups now interchange ideas and strategies, often without direct coordination, it is almost impossible to link their online campaigns to one sole actor, making it extremely difficult to pinpoint from where these tactics originate.

Some officials in Brussels are growing frustrated that the likes of Facebook and Twitter are not doing enough to stop the spread of misinformation and extremist content

"The disinformation campaigns were smart and subtle to focus on issues that mattered to the target audiences," said Chloe Colliver, who heads the digital research unit at the Institute of Strategic Dialogue, a London-based think tank that focuses on extreme speech, who was not involved in the EU report. "They are effective enough so that it's impossible to attribute where the tactics came from."

The EU's analysis of disinformation during the recent electoral campaign follows concerted efforts by the Commission and some European countries to clamp down on how such messaging is spread and shared online. That includes a voluntary code for digital platforms like Facebook, Twitter and Google's YouTube to combat the worst offenders, as well as coordination between officials from EU members states to share how best to address these problems.

While the U.S. tech companies continue to meet the Commission's non-binding standards in terms of tackling fake news, many outside experts and some officials in Brussels are growing frustrated that the likes of Facebook and Twitter are not doing enough to stop the spread of misinformation and extremist content. They say that these companies do not share enough data with outside experts, and that their existing efforts do not go far enough to thwart disinformation campaigns online.

In response, the companies say that they have taken down millions of fake accounts and thwarted hundreds of disinformation campaigns in recent months. Facebook also set up a Europea election "war room" in its European headquarters in Dublin to coordinate its response.

Time, though, may be running out.

As part of its analysis, the Commission said that it would review the voluntary code of practice for platforms at the end of the year to assess if it had had an impact on how false narratives were circulated online.

"Should the results of this assessment not be satisfactory, the Commission may propose further initiatives, including of a regulatory nature," according to the report.