Emmanuel Macron sought to cement his status as favourite for the French presidency Friday on the last day of campaigning before this weekend's run-off election while his far-right rival Marine Le Pen was targeted by protesters on a visit to a cathedral city.

Pro-European centrist Macron and anti-immigration candidate Le Pen have offered starkly different visions for France during a campaign that has been closely watched in Europe and the rest of the world.

At the end of a battle that has increased in intensity in the final days, Macron visited Rodez in the south while Le Pen was heckled in Reims.

Anti-racism protesters hurled objects at Le Pen and ally Nicolas Dupont-Aignan and shouted "Marine, give back the money!" as they left the cathedral in the northern city.

She and her National Front (FN) party are being targeted by several investigations, including one into misuse of expenses in the European Parliament.

Reims is deeply intertwined with French history and Joan of Arc -- a nationalist symbol adopted by the FN.

"Mr Macron's supporters behave violently, even at Reims cathedral, a symbolic and sacred place. No dignity," Le Pen wrote on Twitter.

Polls showed that 39-year-old former investment banker Macron has stretched his lead over Le Pen to 22 points after he was seen to have emerged the strongest from a bad-tempered TV debate on Wednesday.

Macron said he had already chosen the name of his future prime minister -- but even the person concerned had not been informed.

"Yes, this choice has been made 'in petto'," he told Europe 1 radio, using an Italian expression meaning "in my heart".

Macron said he would only announce his choice after he took over from President Francois Hollande, if he wins.

"I will not announce it before," he said.

Le Pen has said she would appoint Dupont-Aignan -- a eurosceptic who was knocked out in the first round of the presidential election -- as her premier if she becomes president.

Eiffel Tower security breach

In a major security breach, Greenpeace activists partially scaled the Eiffel Tower to hang a giant anti-Le Pen banner saying "Liberty, Equality, Fraternity" and "#resist".

The Paris police department said Friday's early-morning protest had exposed "flaws" in the security surrounding the world-renowned monument.

City and police officials announced immediate measures to reinforce patrols at the site, and plans to re-evaluate a video surveillance system.

Security jitters were also raised when a radicalised former soldier was arrested near an army base in Evreux, north of Paris, and weapons including a shotgun were found stashed nearby.

It came at the end of a campaign in which Le Pen has tried to portray Macron as being soft on Islamic fundamentalism, playing to the concerns of many of her supporters after a string of terror attacks in France that have killed more than 230 people since 2015.

Le Pen sees her rise as the consequence of growing right-wing nationalism and a backlash against globalisation reflected in the election of Donald Trump in the United States and Britain's shock vote to leave the European Union.

She has said she wants to copy Britain's example of holding a referendum on France's EU membership, sending alarm bells ringing across the bloc.

She has sought to soften the image of her National Front party over the past six years -- but without fully banishing doubts about the party's core beliefs.

'Fake news'

Macron's campaign team said rumours he has an offshore account in the Bahamas -- which he strongly denies -- were spread on Twitter by accounts close to Kremlin-friendly news sites like Sputnik and RT as well as Trump supporters.

Le Pen repeated the rumours in the TV debate.

Macron's team called it a "textbook case" of "fake news" and has filed a legal complaint and threatened to sue anyone who repeats the claim. Prosecutors are investigating.

Macron won high-profile backing from former US president Barack Obama on Thursday, who said in a video posted on the candidate's website that he "appeals to people's hopes and not their fears".

In the first round of the election on April 23, Macron scored 24 percent with Le Pen second on 21.3 percent.

The bruising contest has seen the main left and right-wing forces in French politics sidelined, as candidates from outside the mainstream parties have profited.