French presidential candidate François Fillon is facing a fresh allegation that he failed to declare a €50,000 (£43,340; $52,900) interest-free loan, reports the BBC.
Le Le Canard Enchaîné newspaper said he was given the loan by businessman Marc Ladreit de Lacharrière 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.
Le Canard Enchaîné says Mr Fillon did not declare the loan from Mr de Lacharrière 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 Lacharriçre 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.