Centrist French presidential candidate Emmanuel Macron has extended his lead in the polls over his far-right rival Marine Le Pen on the final day of campaigning in a tumultuous election race that has turned the country's politics upside down.

Sunday's election is seen as the most important in France for decades, with two diametrically opposed views of Europe and France's place in the world at stake.

The National Front's Le Pen would close borders and quit the euro currency, while independent Macron, who has never held elected office, wants closer European cooperation and an open economy.

The candidates of France's two mainstream parties, which have alternated in power for decades, were both eliminated in the first round of voting on April 23.

An Ifop-Fiducial survey on Friday afternoon, hours before official campaigning closed at midnight, showed Macron on course to win 63 per cent of votes in the second round and Le Pen 37 per cent, the best score for Macron recorded by a major polling organisation since mid-April.

Four other polls earlier in the day put the centrist on 62 per cent and Le Pen on 38 per cent, and a fifth showed Macron on 61.5 per cent, as his second-round campaign gained ground following a stuttering start last week.

Pollsters said Macron had been boosted by his performance in a rancorous final televised debate between the two contenders on Wednesday, which the centrist was judged by French viewers to have won, according to two surveys.

Macron's strong showing in the debate, and another poll this week showing his En Marche! (Onwards!) movement likely to emerge as the biggest party in June legislative elections, have lifted the mood among investors worried about the upheaval a Le Pen victory could cause.

Le Pen was booed by several dozen protesters, including some brandishing Macron posters, as she visited the cathedral in Reims, northern France, where French kings were crowned in the Middle Ages.

Paris's police chief called emergency talks on security before the election after Greenpeace activists scaled the Eiffel Tower on Friday and unfurled a political banner.

Security is a key election issue after attacks by militant Islamists killed more than 230 people in the past two years.

The anti-immigration, anti-EU Le Pen was not giving up.

"My goal is to win this presidential election," she said on RTL radio. "I think that we can win."

A poll on Friday by Odoxa said a quarter of the French electorate was likely to abstain in Sunday's vote, many of them left-wing voters disappointed after their candidates missed reaching the runoff.