Leading French presidential candidate Emmanuel Macron’s team said on Friday it had been the target of a “massive and coordinated hacking attack” that dumped its campaign emails online barely 24 hours before the election.

The centrist candidate’s staff said the release of thousands of emails, accounting documents and other files was an attempt at “democratic destabilization, like that seen during the last presidential campaign in the United States”.

As much as 9 gigabytes of data were posted on a profile called EMLEAKS to Pastebin, a site that allows anonymous document sharing. However, it was not instantly clear who was behind the action or if any of the data was genuine.

Macron’s assistants said the files were stolen weeks ago when several officials from his En Marche party 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.

“Clearly, the documents arising from the hacking are all lawful and show the normal functioning of a presidential campaign,” aides said in a statement.

They further warned that whoever was behind the leak had mixed fake documents with real ones “in order to sow doubt and disinformation”.

The presidential election commission stated that it would hold a meeting later on Saturday after Macron’s campaign informed it about the hack and publishing of the data.

It urged the media to be careful about publishing details of the emails since campaigning is over and since some of the leaked data might be fake, adding that publication could lead to criminal charges.

Senior Le Pen aide Florian Philippot suggested on Twitter that the leak might contain information that the media had deliberately suppressed.