The document dump happened Friday night, less than 48 hours before the country votes in the final round
of the presidential election, which pits the independent centrist Macron against the far-right Marine Le Pen.
The files were released just before 2 p.m. ET Friday, around four hours before the election campaign period officially closed with its restrictions on campaigning, reporting and polling. These restrictions are aimed at preventing last-minute scandals from emerging and influencing the election's outcome.
Around 14.5 gigabytes of emails, personal and business documents were posted to the text-sharing site Pastebin through links to more than 70,000 files, a CNN look at the data shows.
Officials from Macron's En Marche! party said in a statement that the perpetrators of the hack had mixed fake documents with authentic ones "to create confusion and misinformation."
"The leak happened in the last hours of the campaign. This operation is clearly meant to undermine democracy, just like what happened in the US during the last presidential campaign," the statement read.
US intelligence officials have said Russia meddled in the November elections, and Congress is investigating the allegations. Russia has denied any interference.
En Marche! said that some of the files circulating were obtained several weeks ago after personal and professional email accounts were hacked.
It was not clear who was behind the document dump, but the hack targeting Macron's campaign
methods similar to the suspected Russian hacks of the Democratic National Committee last year in United States, according to a report issued in April
by cybersecurity researchers.
Donald Trump won the election after information from Hillary Clinton's campaign was released before the vote.
Other politicians back Macron
If successful Sunday, Macron, at 39, would become the youngest president in the history of France and the nation's youngest leader since Napoleon.
He has led a remarkable campaign, defying the traditional mainstream parties courtesy of his En Marche! movement. For many, however, the campaign has become less about backing Macron and instead about voting against Le Pen, the National Front candidate.
French President François Hollande, Republican candidate François Fillon and the Socialist Party's Benoit Hamon have come together to back Macron, claiming a Le Pen presidency would be disastrous for France.
But Macron also has his critics, who see him as an elite out of touch with the public.
A former economy minister who made millions as an investment banker, Macron has been attacked from both the left and the right for his perceived arrogance.
But two polls released Friday, before polling restrictions went into effect, suggested he still held a 20-point lead.
When asked whether Russia was involved in the Macron email hack, Kremlin spokesman Dmitry Peskov said: "These, like other similar accusations, are based on nothing and are pure slander."
Russian officials have vehemently denied interfering in elections
and have said they have no preferred candidate in the French vote.
Macron's party chief, Richard Ferrand, accused Russia of trying to influence the election by spreading "fake news" about the candidate through its state-controlled media while reporting more favorably on Le Pen.
Russia has good reasons to support Le Pen.
Her anti-Europe and anti-NATO stance are perfectly aligned with Russian interests, and she has consistently called for closer ties with President Vladimir Putin
She has also expressed a desire to roll back European Union sanctions on Russia after Moscow's annexation of Crimea from Ukraine, which she has described as "unfair and silly."
It is a stance that contrasts markedly with Macron, a pro-EU, pro-integration candidate who has said he would keep sanctions on Russia in place, if not add to them.