Doug Stanglin

USA TODAY

France's election campaign commission said Saturday that "a significant amount of data" from the presidential campaign of candidate Emmanuel Macron has been leaked on social networks following an alleged hack attack and warned that anyone spreading such information in the lead-up to Sunday's election could face criminal charges.

The watchdog group said in a statement that the leaked data apparently came from Macron's "information systems and mail accounts from some of his campaign managers." In a statement released after a morning meeting, the commission said the material had been "fraudulently" obtained and that fake news ("des fausses nouvelles") has probably been mingled with it.

The commission urged French media and citizens "not to relay" the leaked documents "in order not to alter the sincerity of the vote." It said spreading of such data "is liable to be classified as a criminal offense."

Under French law, the candidates and the media are under a 44-hour legal blackout beginning Friday at midnight until the last polling station is closed on Sunday. The law bars any campaigning and media coverage seen as swaying the election.

While the law will keep most of the leaked material out of the mainstream media, it will be difficult to curtail its spread on social media. The law also bars the two presidential runoff candidates, Macron and Marine Le Pen, from commenting on the developments.

Voting already has begun in some French territories, starting with Saint-Pierre-et-Miquelon, an archipelago located near Newfoundland, and will also take place in French embassies abroad ahead of voting in France itself on Sunday.

The election pits centrist Macron’s business-friendly, pro-European vision again far-right Le Pen’s protectionist, closed-borders view that resonates with workers left behind by globalization. The outcome could have profound implications for the future of the battered European Union.

The Macron campaign, which warned weeks ago that its computers had been breached, said late Friday that data from the purported hack was dumped online only an hour before the blackout, hamstringing any full response.

With only minutes to spare, Macron's political movement, known as En Marche, issued a statement saying the unidentified hackers gained access to staffers' personal and professional emails and leaked campaign finance material and contracts — as well as fake decoy documents — online.

Florian Philippot, the No. 2 in Le Pen's anti-immigration National Front party, asked in a tweet: "Will the #Macronleaks teach us something that investigative journalism deliberately buried?"

The perpetrators remain unknown. While the hack is shaking up the already tumultuous campaign, it is unclear whether the document dump would affect Macron's sizable poll lead over Le Pen going into the vote.

The prestigious French newspaper Le Monde published a statement below all election stories online noting the release of the purported Macron documents on the Internet, saying it was "clearly aimed at disrupting the current electoral process."

Le Monde said it would not publish the contents of any of the documents until after the election because of the sheer volume (15 gigabytes), the difficulty in crosschecking their validity, and "most importantly, because these files were knowingly published 48 hours before the vote, with the obvious purpose of damaging the sincerity of the ballot."

If the documents provide to be valid, the newspaper said, it will publish them "in accordance with our journalistic and ethical rules, without being made a tool of anonymous actors' publishing schedules."

The hack was reminiscent of the intrusion into the computers of the Democratic National Committee and some of Democratic Party candidate Hillary Clinton's staffers before the U.S. presidential election.

WikiLeaks, which was instrumental in spreading the hacked Clinton material, was also playing a role in helping disseminate the French data. In a tweet Friday night, WikiLeaks provided links to the voluminous Macron material.

U.S. Intelligence services have blamed Russia and its surrogates for the U.S. hacking, but it was not immediately clear who was responsible for the French intrusions..

Contributing: Associated Press