The European Union says that it has gathered evidence of "continued and sustained" disinformation activity by Russia aimed at influencing the results of May's elections for the European Parliament.
The European Commission report said "Russian sources" tried to suppress voter turnout and influence voters' preferences.
It did not elaborate on what it meant by "Russian sources," and it said it was not yet able to identify a "distinct cross-border disinformation campaign from external sources specifically targeting the European elections."
"The number of disinformation cases attributed to Russian sources...doubled as compared to the same period a year ago," Security Commissioner Julian King told a news conference in Brussels highlighting the report.
"So almost 1,000, as compared with over 400," King said, adding that EU steps to counter disinformation might have also had "some sort of deterrent effect."
Justice Commissioner Vera Jourova told the same news conference that there was "no big-bang moment" -- like the Cambridge Analytica scandal -- to draw attention to organized manipulation.
In that case a whistle-blower's revelations showed that tens of millions of users had their personal Facebook data seized by Cambridge Analytica.
The European Commission report follows preelection warnings from Brussels to EU countries and social-media companies like Facebook and Twitter to guard against possible "fake news" from Russia.
Malign activities noted in the report ranged from challenging the EU's democratic legitimacy to exploiting divisive debates on issues like migration.
It cited the example of the fire at the Notre Dame Cathedral in Paris, which was used by malicious actors "to illustrate the alleged decline of Western and Christian values in the EU."
King also mentioned what he said were false claims in social-media postings by Russian sources that the EU had made Poland poorer than during communism.
He also said that Russian sources on social media, without identifying them, suggested French President Emmanuel Macron wants to expel some countries from the EU, and mentioned a fake Twitter account allegedly linked to Russia that has spread false information that the EU has Nazi roots.
The commission said its efforts to combat "fake news" had helped reduce the amount of disinformation appearing online.
Those efforts include signing up Internet companies like Facebook, Google, Twitter, and Mozilla to a voluntary code of conduct.
But the report said more needed to be done.
"The tactics used by internal and external actors, in particular linked to Russian sources, are evolving as quickly as the measures adopted by states and online platforms," the commission wrote.