PARIS - France sought to keep a computer hack of frontrunner Emmanuel Macron's campaign emails from influencing the outcome of the presidential election, with the electoral commission warning on Saturday that it may be a criminal offense to republish the data.

Macron's team said a "massive" hack had dumped emails, documents and campaign financing information online just before campaigning ended on Friday and France entered a quiet period, effectively forbidding politicians from commenting on the leak.

Polls have been predicting that Macron, a former investment banker and economy minister, is on course for a comfortable win over far-right leader Marine Le Pen in Sunday's election, with the last surveys showing his lead widening to around 62 percent to 38.

"We knew that this kind of risk would be present during the presidential campaign, because it has happened elsewhere. Nothing will be left without a response," President Francois Hollande told French news agency AFP.

The election commission, which supervises the electoral process, warned social and traditional media not to publish the hacked emails lest they influence the vote outcome.

"The commission stresses that publication or republication of these data ... could be a criminal offense," it said in a statement.

Russia has been blamed for the attack, a charge denied by the Kremlin.

Reuters