Macron has maintained his centriest position over Le Pen, according to surveys conducted by French pollsters.
He garnered 24 percent of the vote April 23 during the first round of balloting as he beat his nearest rival, National Front's Marine Le Pen, who won 21 percent. "We have identified several of these hackers and have sent all the relevant data to the police in the context of a complaint", Le Pen's campaign manager David Rachline and communication chief Gaetan Bertrand said on Thursday.
"The former traditional parties are all blackballed", Le Pen told the AP.
Nicola McGeady of Ladbrokes says with "so many political upsets in recent times, we are not surprised to see punters ignoring the polls".
Macron's En Marche! (On The Move) party said in a statement that the leaks came "in the last hour of the official campaign" and were "clearly" aimed at "democratic destabilization, like that seen during the last presidential campaign in the United States".
It urged French media and citizens "not to relay" the contents of the leaked documents "in order not to alter the sincerity of the vote".
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Mr Macron and Ms Le Pen won through to the run-off after a first-round last month which saw nine other candidates eliminated.
Donald Trump won the election after information from Hillary Clinton's campaign was released before the vote.
Meanwhile, voting for France's next president started in some overseas territories.
On the eve of the most consequential French election in decades, the staff of the presidential candidate Emmanuel Macron said on Friday evening that the campaign had been targeted by a "massive and coordinated" hacking operation, one with the potential to destabilize the nation's democracy before voters go to the polls Sunday.
About 14.5 gigabytes of emails, personal and business documents were posted, a CNN look at the data shows.
The perpetrators remain unknown.
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Macron is considered the frontrunner in the second round of the presidential election, where he faces far right populist Marine Le Pen. Even if she loses in Sunday's runoff, she is likely to be a powerful opposition figure in France's parliamentary election in June. The Kremlin however denied all such claims in February saying Russian Federation was not behind any such attacks.
But Russia has good reasons to support Le Pen over Macron. "Madame Le Pen exploits anger and hatred". They fear her party's racist past, while worrying that his platform would demolish job protections for workers or be too much like his mentor, the deeply unpopular outgoing President Francois Hollande.
Cyber security firm Trend Micro, said last month a hacking group, believed to be part of a Russian intelligence unit, was targeting Macron and his campaign team, adding that it appeared to be the same Fancy Bear group behind the hacking of Democratic campaign officials before last year's U.S. presidential election.
USA far-right circles were abuzz with the news that Mr Macron's campaign had been hit by a massive disclosure, but the news comes soon after a crude forgery was circulated on an online message board popular with pranksters and extremists. (Onwards!) confirmed that it had been hacked.
The Le Pen campaign did not release a comment before the blackout began, but her top aide was promoting the hashtag #MacronLeaks on Twitter earlier on Friday.
As Bitter French Campaign Ends, Macron's Team Hit by Hack
Macron's political movement, En Marche!, has released a statement confirming that the candidate and his campaign team were hacked. Hillary Clinton's U.S. presidential campaign suffered similar leaks and also said authentic documents were mixed with false ones.