A preliminary investigation into claims that the wife of French presidential candidate Francois Fillon received public money improperly has been launched, French prosecutors have said.
It comes after Le Canard Enchaine claimed Penelope Fillon earned about 500,000 euros (£430,000) as her husband's assistant in Parliament.
The newspaper has questioned how much work she did for the money.
Mr Fillon said he was "outraged by the contempt and misogyny" in the story.
Le Canard Enchaine alleged that Mrs Fillon, who was born in Wales, had been paid from money available to her husband as an MP for the Sarthe region in northern France.
The newspaper, which said it had access to her payslips, claimed that she earned a total of about 500,000 euros in three periods between 1998 and 2012. But it said reporters had been unable to find any witnesses to her work.
In a press release, the national financial prosecutor's office said it had opened a preliminary investigation into suspicions of "embezzlement of public funds, misuse of company assets and concealment of these offences".
Wasteful public spending
But speaking to reporters at a campaign event in Bordeaux, centre-right presidential candidate Mr Fillon compared the newspaper report to a stink bomb.
He said: "I won't make any comment because there is nothing to comment on. But I'm outraged by the contempt and the misogyny in this story. Just because she is my wife she should not be entitled to work?"
Mr Fillon's staff have previously said that his wife worked for him in a common and legal arrangement used by many MPs.
The BBC's Paris correspondent, Hugh Schofield, said the story had potential to do serious damage to the Fillon campaign - reminding a public that feels deeply hostile to establishment politicians that the candidate is very much part of the system.
The 62-year-old candidate for the right-wing Republicans party has criticised wasteful public spending and plans to cut 500,000 civil service jobs if elected.
Mr Fillon is the front-runner for the presidential election in April, with National Front leader Marine Le Pen and centrist Emmanuel Macron as his main challengers.
Benoit Hamon, who is expected to win the Socialists' primary, told French public TV that close relatives of politicians should not be paid from parliamentary funds.
"Lawmakers should not be allowed to hire their children, cousins, relatives or wives anymore," he said.