Voter turnout at 26.1% at midday in French presidential elections

The two candidates for France's presidential runoff have cast their ballots and basked in adoring crowds outside their polling stations.

Far-right leader Marine Le Pen went first, cheerily greeting election workers in the northern town of Henin-Beaumont, in France's struggling former industrial heartland.

She emerged from the ballot booth beaming to drop it in a transparent box. Outside, she took selfies with supporters.

Then came incumbent Emmanuel Macron, who shook dozens of hands and was handed a small child to hold up on his journey from his family home in the resort town of Le Touquet on the English Channel to his voting station.

Inside, he greeted yet more people, posed for photographs with his wife Brigitte, and cast his ballot with a wink for the cameras.

The voting booths were shielded by curtains in the red-white-and-blue of the French flag.

About 48.8 million voters are eligible to take part in the runoff, which is being watched around Europe. Early results are expected Sunday night.

Turnout in the Sunday round is slightly higher than it was at the same point in the first-round vote two weeks ago.

Participation is at 26.1 per cent at midday Sunday. Many of those expected to choose the incumbent leader are doing so to keep out Marine Le Pen and ideas seen as too extreme and anti-democratic, such as her plan to ban the Muslim headscarf in public, or her ties to Russia.

All recent opinion polls converge toward a win for the 44-year-old pro-European Macron yet the margin over his 53-year-old far-right rival varies broadly.

The result of voting in France, a nuclear-armed nation with one of the world's biggest economies, could also impact the conflict in Ukraine, as the nation has played a key role in diplomatic efforts and support for sanctions against Russia.