Emmanuel Macron

The second round contest pits centrist Emmanuel Macron, a 39-year-old former investment banker, against the far-right nationalist Marine Le Pen, 48.

Citizens in some overseas territories and many French expats abroad have begun voting.

The polls open in metropolitan France at 08:00 local time (06:00 GMT) on Sunday and close at 19:00 (17:00 GMT).

Polling stations will remain open in some big cities until 20:00 local time (18:00 GMT), with early estimates of the result due to be reported immediately after they close.

Campaign officials said the perpetrators of the hack -- revealed just two days before the election -- had mixed fake documents with authentic ones "in order to create confusion and misinformation."

About 14.5 gigabytes of emails, personal and business documents were posted, a CNN look at the data shows. Links to the 70,000-plus files were posted on pastebin, a text-sharing site, just before 2 p.m. ET Friday.

The campaign said that genuine files were mixed up with fake ones in order to confuse people.

It said that it was clear the hackers wanted to undermine Mr Macron ahead of Sunday's second round vote.

The centrist will face off against far-right candidate Marine Le Pen.

The documents were leaked on a file sharing website late on Friday, as the official presidential campaigning period drew to a close.

What was released?

About nine gigabytes of data were posted online by an anonymous user.

Mr Macron, a former banker, is seen as a political outsider, having never run an election campaign before.

After topping Sunday's vote, he is now favourite to win the run-off on 7 May.

It is the first time in six decades that neither of France's main left-wing or right-wing parties has a candidate in the second round.

With 97% of votes counted, Mr Macron stands at 23.9% with Ms Le Pen on 21.4%.

Their nearest challengers, centre-right François Fillon and hard-left Jean-Luc Mélenchon, fell behind, with just over 19% each.