France's centre-right presidential candidate François Fillon has apologised for using state funds to pay family members.
The 62-year-old hopeful was the favourite to defeat Front National's Marine Le Pen until the satirical weekly Le Canard Enchaine accused him of paying his wife Penelope Fillon more than €500,000 (£430,000) for jobs she may have not done.
It has also been revealed he paid his two children as legislative assistants. However, Fillon has maintained no rules were broken.
In France, it is legal and commonplace for MPs to hire family members as long as they are genuinely employed. However, Fillon has said that practice may no longer be acceptable and that he made a "mistake".
Speaking to reporters in Paris, he said: "Being courageous in politics means admitting your mistakes.
"Using your family members as parliamentary assistants is a perfectly legal practice, but what was acceptable in the past is no longer acceptable.
"By working with my wife and two children, I was mindful of this relationship of trust, but today it causes mistrust and that was a mistake. I regret it profoundly and I apologise to the French people."
Fillon, the former prime minister, was the favourite to prevail in the presidential race, partly because he was seen as an honest politician.
However, since the leaks polls suggest he may be eliminated in the first round of voting in April's election, sparking a run-off between centrist Emmanuel Macron and far-right leader Marine Le Pen.
Some figures in Fillon's Republican party have called for him to step aside for another candidate, but he has remained resolute that he will remain in the race.
He previously stated he would resign if investigators launched a formal investigation, and claimed the accusations were "carefully prepared" to destroy him.