The European Union’s foreign policy chief has warned Russia against carrying out “malicious cyber activities” on the eve of elections in Germany that Berlin fears are being targeted by Kremlin-backed hackers.

Hackers have tried to steal data and access the personal accounts of government officials, politicians, journalists and activists, Josep Borrell said in a statement Friday, calling the efforts attempts to “undermine our democratic institutions and processes.” He linked the attacks to the Ghostwriter hacking group, which German officials have said is associated with Russia’s military intelligence service the GRU.

Borrell did not say which of the bloc’s members had been attacked. But Germans will vote on Sunday for a leader to replace Chancellor Angela Merkel, who is retiring. Berlin has previously expressed concern that Russia could try to undermine German democracy or sway public opinion toward Moscow-friendly candidates, possibly by releasing disinformation or sensitive communications obtained through hacks.

Russia has a keen interest in the results of Sunday’s polls. The foreign policy of Germany, Europe’s richest country and a member of NATO, has ripple effects on relations between Russia and the West. Under Merkel, Germany’s relationship with Russia has, at times, been strained or even antagonistic. But she has tried to separate concerns about Moscow’s expansionism and poor human rights record from issues of trade and economics.

By contrast, Germany’s next government could include members that advocate a firmer stance. The center-left Social Democrats and Merkel’s center-right Christian Democrats are neck-and-neck in opinion polling, but the Green Party, which also is likely to play some role in the next government, has pledged to increase political pressure on Russia if it takes office. The Greens were targeted by a vicious social media campaign this year that a senior party official told the Guardian newspaper had been orchestrated by the Kremlin.

The Russian mission to the European Union did not immediately respond to a request for comment. Moscow has repeatedly denied Western allegations of election interference, saying it never has and never will interfere in foreign elections.

Borrell’s remarks came on the same day that the German Interior Ministry reported a cyberattack on a government office tasked with overseeing the weekend election, the Associated Press reported.

“As far as we can tell at the moment, the internal election server wasn’t affected by this attack and as such there is no threat to the conduct of the federal election,” an Interior Ministry spokesman said.

In July, the head of Germany’s domestic intelligence service warned that the upcoming elections were a “significant” target for foreign espionage agencies that wanted to influence the results. Agency head Thomas Haldenwang said that there had been an increase in attacks on the email accounts of German legislators and their staffers but that little harm appeared to have been done.

Russia and the Ghostwriter group also appeared to be behind at least some of those campaigns, European officials said.

Alongside attempts to obtain private information, Ghostwriter has sought to distribute disinformation via falsified news articles and op-eds to sow distrust in Eastern Europe against the United States and Western Europe, according to FireEye, a major U.S. cybersecurity firm.

FireEye researchers said there was evidence that Ghostwriter hackers had created false personas with Baltic or English-sounding names, which then published disinformation. In one instance, hackers fabricated an interview transcript that falsely showed a senior U.S. Army general criticizing Polish and Baltic allies.

In another, a fake letter purporting to be from the NATO secretary general that announced the alliance was withdrawing from Lithuania because of the coronavirus pandemic was published on a blog that falsely claimed to be written by a local journalist, researchers said.