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The front-runner in the French presidential election has told the Eyes On Events that the EU must reform or face the prospect of "Frexit".
Pro-EU centrist Emmanuel Macron made the comments as he and his far-right rival Marine Le Pen entered the last week of campaigning.
French voters go to the polls on Sunday to decide between the pair.
Ms Le Pen has capitalised on anti-EU feeling, and has promised a referendum on France's membership.
She won support in rural and former industrial areas by promising to retake control of France's borders from the EU and slash immigration.Image copyright AFP Image caption Emmanuel Macron, pictured at Paris' Holocaust memorial, is pro-European
"I'm a pro-European, I defended constantly during this election the European idea and European policies because I believe it's extremely important for French people and for the place of our country in globalisation," Mr Macron, leader of the recently created En Marche! party, told the Eyes On Events.
"But at the same time we have to face the situation, to listen to our people, and to listen to the fact that they are extremely angry today, impatient and the dysfunction of the EU is no more sustainable.
"So I do consider that my mandate, the day after, will be at the same time to reform in depth the European Union and our European project."
Mr Macron added that if he were to allow the EU to continue to function as it was would be a "betrayal".
"And I don't want to do so," he said. "Because the day after, we will have a Frexit or we will have [Ms Le Pen's] National Front (FN) again."
Both Mr Macron - who is leading in the polls by 20 percentage points - and Ms Le Pen spent Sunday campaigning around France.
Marine Le Pen
Last updated April 25, 2017*Polling results up to this date show how people said they would vote on 7 May, if Macron and Le Pen reached the second round
The polling average line looks at the five most recent national polls and takes the median value, ie, the value between the two figures that are higher and two figures that are lower.
Mr Macron visited Paris's Holocaust memorial, where he paid his respects. Sunday was France's national day of remembrance for the French Jews who were deported to Nazi Germany during the Second World War.
The war has proved a difficult area for Ms Le Pen. She suggested earlier this month France was not responsible for a 1942 wartime round-up of 13,000 Jews, who were sent from France to Nazi death camps.
Meanwhile, Jean-François Jalkh - the man she named as interim president of the FN while she campaigned - was forced to step down on Tuesday amid claims he had questioned the reality of Nazi gas chambers in the past. He denies any wrongdoing.
It was an unwelcome development for Ms Le Pen, who has worked hard to distance her party from its anti-Semitic roots.Image copyright EPA Image caption Marine Le Pen has won support from people unhappy with the EU
She laid a wreath at the World War II monument in Marseille, after visiting an aluminium plant in the nearby town of Gardanne.
The plant is known for dumping toxic waste into the Mediterranean. It was given six years to reach compliance with EU norms last year, after improving its filtering process.
While there, Ms Le Pen said she would pursue a vision of "true ecology", saying she wanted to "make the link between the choice of economic model and environmental and health problems".