French presidential far-right candidate Marine Le Pen fought off accusations of plagiarism on Tuesday as supporters of her rival Emmanuel Macron warned that a high abstention rate could hurt his chances of victory.

It emerged that Le Pen had copied parts of her fiery May Day speech from one made on April 15 by Francois Fillon, the conservative candidate who was eliminated in the first round of the election last month.

In the speech in question, Fillon paid tribute to the French language and spoke of a third ‘French way’ for the 21st century.

Analysis by the Ridicule TV YouTube channel showed that the nationalist Le Pen repeated these passages almost verbatim in her speech on Monday.

Florian Philippot, the vice president of Le Pen's National Front (FN) party, said it was ‘not plagiarism’, but ‘a nod to a short passage in a speech about France’.

Le Pen's spokesman David Rachline said the copied passages in the speech were ‘appreciated by Fillon's voters’.

Just days ahead of Sunday's keenly-watched runoff, 39-year-old Macron remains the frontrunner, with polls predicting a 19-point lead, putting him on track to become France's youngest president.

Amid concerns in his camp that a high abstention rate could help Le Pen's chances, company bosses, celebrities and scientific researchers called in newspaper editorials for people to vote for Macron, a pro-EU former investment banker who styles himself as ‘neither of the left nor the right’.

- Call to left-wing voters -

Macron's economically liberal approach worries many voters on the left. While they will not back Le Pen, many say they will stay at home rather than vote for him and polls say abstention could be as high as 30 percent.

Former Greek finance minister Yanis Varoufakis, an emblematic figure of the radical left in Europe, urged left-wingers to vote for Macron because he was ‘the only minister in Europe who did everything possible to help us’ during the Greek debt crisis in 2015.

Varoufakis told Le Monde newspaper that in June 2015, as the European Union, the International Monetary Fund and the European Central Bank were putting pressure on Greece over its debt mountain, then-economy minister Macron convinced French President Francois Hollande to reopen negotiations.

He said Macron ‘offered to come to Athens incognito’ for talks, but Hollande stopped him. Macron ‘was the only member of the 'system' who opposed’ the harsh stance on Greece, Varoufakis said.

Varoufakis' support is significant because hard-left French firebrand Jean-Luc Melenchon, who scored 19.6 percent in the first round of the election in April, is close to current leftist Greek Prime Minister Alexis Tsipras.

Daniel Cohn-Bendit, a veteran rebel of French politics, called on Melenchon's supporters to put aside their ‘hatred’ of Macron.

‘Think rationally and vote for Emmanuel Macron and defend democracy and freedom,’ the former ecologist Euro MP told Europe 1 radio.

Le Pen and Macron will face off Wednesday in what promises to be a fiery TV debate when the far-right leader is likely to sharpen her attacks on a candidate she says embodies ‘the world of finance, of arrogance, of money as king’.

Macron fought off accusations from Le Pen that he was controlled by banks.

‘I am not under the thumb of the banks. If I were, I would have continued to work for them,’ he told BFMTV news channel on Tuesday.

Macron said he had received similar insults from the far left and far right for months, ‘but I'll look them straight in the eye and say I don't have any lessons to learn from them’.

In a feisty speech on Sunday, Macron told thousands of his supporters he would defend ‘free democracy’ if voters choose him.

He said he was aware that ‘many people will vote for me to avoid having the National Front’.

‘I say to them that I am completely aware that on May 7, I will be doing more than defending a political programme -- I will be leading the fight for the republic and for a free democracy,’ he said.