French National Front political party leader and candidate Marine Le Pen delivers a speech after results in the Nord-Pas-de-Calais-Picardie region for the second-round regional elections in Henin-Beaumont, France, December 13, 2015. [Photo/Agencies]

PARIS - Marine Le Pen's far-right National Front did not win any region in French elections on Sunday, in a setback to her hopes of being a serious presidential contender in 2017.

The regional election run-off, in which the conservatives won seven constituencies and the Socialists five, was no real victory for either of these two mainstream parties, shaken by the far-right's growing appeal to disillusioned voters.

Boosted by fears about security and immigration after the Islamist militant attacks in Paris a month ago that killed 130 people, the National Front (FN) had won more votes than any other party nationally in last week's first round.

Although it won no region on Sunday after the Socialists pulled out of its key target regions and urged their supporters to back the conservatives of former President Nicolas Sarkozy, the FN still recorded its best showing in its history.

"Tonight, there is no place for relief or triumphalism," Socialist Prime Minister Manuel Valls said. "The danger posed by the far right has not gone away; far from it."

Sarkozy struck a similar theme, calling the strong FN showing a "warning sent to all politicians, ourselves included, in the first round".

"We now have to take the time for in-depth debates about what worries the French, who expect strong and precise answers," he said, citing Europe, unemployment, security and national identity issues.

Le Pen, who had hoped to use regional power as a springboard to boost her chances in 2017 presidential elections, lost by a huge margin in northern France on Sunday, where she led her party's ticket, attracting 42.8 percent of the votes in the run-off vs 57.2 percent for the conservatives.