A growing majority of French voters see Marine Le Pen's far-right National Front as a threat to democracy, while a third approve of its ideas, a Kantar Sofres-Onepoint poll showed on Tuesday.

Le Pen, who most polls see coming on top in the first round of France's presidential election, has sought to make the anti-European Union, anti-immigrant National Front less of a fringe party since she took its reins from her father in 2011.

However, 58 percent of those surveyed in the poll for Le Monde and France Info radio said the party was a threat to democracy. After shrinking for a decade, that number has been rising since 2013, when it stood at 47 percent.