France's election campaign commission said Saturday that it is examining the reported hacking attack on candidate Emmanuel Macron's political movement and subsequent document leaks online.
It urged French media not to publish the documents, warning that some of them are "probably" fake. It also urged citizens not to relay the data on social media to protect the integrity of the French vote.
French electoral law imposed a blackout Saturday and most of Sunday on any campaigning and media coverage seen as swaying the election, to allow voters a period of reflection before casting their ballots.
The Macron team asked the campaign oversight commission Saturday to bring in cybersecurity agency ANSSI to study the hack, according to a government official who spoke to The Associated Press on condition of anonymity because they weren't authorized to discuss the details publicly.
ANSSI can only be called in for cases where the cyberattack is "massive and sophisticated" — and the Macron hack appears to fit the bill, the official said.
Someone on 4chan — a site known, among other things, for cruel hoaxes and political extremism — posted links to a large set of data Friday night.
Macron is seen as the favorite going into Sunday's runoff against far-right leader Marine Le Pen, with most polls showing him leading the National Front candidate by double digits.
The hacking incident comes at time when many have said that the future of the European Union and its currency, the Euro, hang in the balance depending on what voters decide Sunday.
Macron, a former investment banker and centrist, is widely seen as being pro-immigration and in favor of continuing and strengthening the European Union.
Le Pen, a hard-right nationalist, is in favor of closing borders and protecting the French economy from the force of globalization. She is the daughter of Jean-Marie Le Pen, a convicted Holocaust denier who has dismissed the Nazi gas chambers as a "detail of history."
Fears of hacking, fake news manipulation and Russian meddling clouded the French campaign but had largely gone unrealized — until late Friday's admission by Macron's campaign that it had suffered a coordinated online pirate attack had led to the leak of campaign emails and financial documents. It was unclear who was behind the hack and the leak.
U.S. intelligence agencies said they have definitive evidence that Russia was behind the hacking of Democratic email accounts, with the aim of benefiting Donald Trump's campaign and harming his Democratic opponent, Hillary Clinton.
Putin has long denied such claims. On Tuesday, during a tense meeting with German Chancellor Angela Merkel, the Russian president was forced to again deny reports of Russian meddling in international elections.
Merkel said she was confident that Germany can weather any disinformation campaign targeting Germany's upcoming election. Asked about the threat during the news conference, she cited two recent incidents of what she described as "gross misinformation."
Le Pen, meanwhile, told The Associated Press that she believes she can pull off a surprise victory in the high-stakes vote that could change Europe's direction.
Le Pen has lately played down her plans to quit the EU and the euro, saying this may not be her top priority. But if she wins, the euro will fall around 5 percent in the immediate aftermath, a Reuters poll found this week.
A campaign blackout starting minutes after the Macron team announcement means that Le Pen's campaign can't legally comment on the leak.
In a statement, Macron's En Marche movement said the hack took place a few weeks ago, and that the leaked documents have been mixed with false documents to "seed doubt and disinformation" and destabilize Sunday's presidential runoff. Hillary Clinton's U.S. presidential campaign suffered similar leaks, and also said that authentic documents were mixed with false documents.
The documents' release just before France enters a roughly two-day-long blackout means that the leak may have very little impact beyond the overheated world of Twitter and Reddit.
On the other hand, the messages' release just before France's political machinery shuts down for the weekend might mean that talk of the leak - regardless of its veracity - will dominate dinner table conversations as French voters make up their minds Saturday.
The candidates stopped campaigning at midnight Friday to give voters a day of reflection before the election. It's a stark choice: Le Pen's anti-immigration, anti-European Union platform, or Macron's liberal, pro-EU stance.
From depressed northern France to the streets of Paris, few voters seemed aware Saturday of the hacking attack on Macron's team — although several were looking forward to the end of a vitriolic campaign.
In Henin-Beaumont in northern France, where Le Pen will cast her ballot on Sunday, 28-year-old Thomas Delannoy said the campaign "looks like reality TV." The construction painter called the electoral process "laughable," saying that neither candidate had a platform he could identify with.
Macron will vote Sunday in the seaside town of Le Touquet, where his wife Brigitte went for a walk Saturday with her daughter and grandchildren.
The Associated Press contributed to this report