French presidential candidate Francois Fillon is facing a fresh allegation that he failed to declare a €50,000 (£43,340; $52,900) interest-free loan.
Le Canard Enchaine newspaper said he was given the loan by businessman Marc Ladreit de Lacharriere in 2013.
Mr Fillon’s lawyer told the weekly the loan did not need to be declared and had been repaid in full.
On Sunday, Mr Fillon said he would fight on in the race, despite a formal embezzlement investigation against him.
Leaders of his centre-right Republican party then unanimously backed him.
Latest opinion polls suggest that Mr Fillon would be eliminated in the first round of the presidential elections on 23 April, finishing third behind far-right leader Marine Le Pen and liberal Emmanuel Macron.
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What are the new allegations?
Le Canard Enchaine says Mr Fillon did not declare the loan from Mr de Lacharriere to the country’s state transparency watchdog.
Mr Fillon “did not deem it necessary” to report the loan, the newspaper says in its edition due to hit the stands on Wednesday.
Mr Fillon’s lawyer Antonin Levy is then quoted by the weekly as saying the loan did not need to be declared and was repaid in full.
Mr Ladreit de Lacharriere was awarded France’s highest state honour in 2011 – when Mr Fillon was prime minister.
The billionaire businessman has been questioned by financial police over allegations that he paid Mr Fillon’s wife Penelope about €100,000 for a couple of book reviews when she worked for his literary magazine La Revue des Deux Mondes.
Mr Ladreit de Lacharriere denies her work was fictitious and says he did ask her to write for the magazine.
Mrs Fillon says her job was genuine and she did produce notes on the books.
What are the embezzlement accusations against Fillon?
The allegations – also first reported by Le Canard Enchaine – have been rumbling on for more than a month now.
Mr Fillon has fought the allegations that his Welsh-born wife, Penelope, was paid for a number of years for work that she did not do as his parliamentary assistant.
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However Mrs Fillon, who insists she did work for her husband, has told French magazine Journal du Dimanche that “everything was legal and declared”.
Also under scrutiny are claims that two of the children, Marie and Charles, were paid by their father’s office for legal work even though they had not yet qualified as lawyers.
Mr Fillon told French TV in January that he had hired his children for their expertise, the Guardian reports.