Quick guide: The French presidential election

It urged French media not to publish the documents, warning that some of them are "probably" fake.

Macron's team said the files were stolen weeks ago when several officials from En Marche! had their personal and work emails hacked - one of "an intense and repeated" series of cyber-attacks against Macron since the launch of the campaign.

In January, US intelligence said that Russian President Vladimir Putin had ordered hacking of the Democratic National Committee and the chairman of Hillary Clinton's Democratic campaign to influence the election on behalf of Donald Trump.

France's election campaign commission said Saturday "a significant amount of data" has been leaked on social networks following a hacking attack on centrist Emmanuel Macron's presidential campaign.

Wikileaks indicated that it was not responsible for the leak itself but did not say where it obtained the documents.

The leaked data was posted just a day and a half days before voters go to the polls to decide who will be France's next leader.

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.

Ben Nimmo, a UK-based security researcher, said initial analysis suggested that online activists affiliated with American far-right groups had been behind early efforts to spread the leaked Macron emails on social media.

Macron, who extended his lead in the polls over Le Pen on Friday, is seen as the frontrunner in an election billed as the most important in France in decades.

It is a stance that contrasts markedly with Macron, a pro-EU, pro-integration candidate who has said he would keep sanctions on Russian Federation in place, if not add to them.

Tensions marred the race right to the end. At the time, the campaign said the hackers were unsuccessful.

Le Pen, 48, has brought her far-right National Front party, once a pariah for its racism and anti-Semitism, closer than ever to the French presidency, seizing on working-class voters' growing frustration with globalization and immigration. She claimed an "ideological victory" and said she could still win on Sunday.

Someone on 4chan - a site known, among other things, for cruel hoaxes and political extremism - posted links to a large set of data which was said to have come from Macron's campaign.

On Sunday she faces 39-year-old centrist Emmanuel Macron, who also helped upend France's traditional political structure with his wild-card campaign.

The documents' release just before France enters a roughly two-day-long blackout - during which politicians, journalists and even ordinary citizens are meant to pull back from any public election talk to avoid swaying the vote - means that the leak may have very little impact beyond the overheated world of Twitter and Reddit.

Many voters, however, do not like either candidate.

The seasoned campaigner Marine Le Pen seems to have polished her image ahead of the Sunday May 7 2017, runoff presidential election, although her background and driving ambition has moulded her over many years of political campaigning.

The French presidential election campaign is not the first to be overshadowed by accusations of manipulation via computer hacking and cyber-attacks.

She said, win or lose, "we changed everything".

"The seriousness of this event is certain and we shall not tolerate that the vital interests of democracy be put at risk", it added.

And Le Pen holds several pro-Russia positions, including lifting European Union sanctions against the country, which would benefit Putin.

She "speaks for no one".

  • Leroy Wright