A former aide to the French far-right presidential candidate, Marine Le Pen, has made new allegations about fraudulent party financing, reports the BBC.
Gaël Nofri said that in 2012 the National Front (FN) had recruited him into Ms Le Pen's presidential campaign team, using a fictitious European Parliament (EP) contract.
It was apparently a way for the FN to avoid declaring campaign spending.
The FN is already under investigation for alleged misuse of EP funds.
Polls suggest that Ms Le Pen is on course to win the first round of the presidential election in April, but centrist Emmanuel Macron is gaining ground and looks likely to beat her in the May runoff vote.
A Figaro/LCI poll on Sunday put Mr Macron on 58% in the runoff, against 42% for Ms Le Pen.
Quoted by French media, Mr Nofri said he had signed up to work for Ms Le Pen in September 2011.
"In 2012 I was told: 'there is a problem, we have to do it via a European Parliament contract' - I refused," he said.
Mr Nofri is now a municipal councillor in Nice with the centre-right Republicans party, having severed his links to the FN.
Later in 2012, he said, he was given a contract to work with FN accountant Nicolas Crochet, but he "never set foot" in Mr Crochet's office.
The French news website Mediapart says fraud investigators have found evidence of €4,500 (£3,834; $4,763) in monthly payments to Mr Nofri from 2012, identifying him as a European Parliament assistant to MEP Jean-Marie Le Pen, Marine's father and the former FN leader.
"I was never Jean-Marie Le Pen's assistant," he said.
At least three other FN associates of Marine Le Pen are under French judicial investigation: Catherine Griset, Frédéric Chatillon and her bodyguard Thierry Legier.