French centre-right presidential candidate Francois Fillon has said he will fight on, as he announced that a judge was placing him under formal investigation.
For weeks, he has fought allegations that his wife was paid for years for work she did not do.
He has now been summoned to appear before the judge, Serge Tournaire, on 15 March.
“It’s a political assassination,” Mr Fillon complained.
“But it’s not just me that is being assassinated, it’s the presidential election. The voices of millions of votes have been muzzled.”
Mr Fillon said he would respect the summons and tell the judge the truth.
In a combative speech, the Republican candidate vowed not to give in but to fight to the end, urging voters to follow him.
Who is Francois Fillon?
A former prime minister during Nicolas Sarkozy’s presidency, he was selected late last year in national primaries held by the centre-right Republicans that attracted some four million voters.
For a time he was the favourite in the race to succeed Francois Hollande as president, but then came the “fake jobs” allegations in satirical weekly Le Canard Enchaine.
He has slipped to third in the polls, behind far-right National Front (FN) leader Marine le Pen and centrist Emmanuel Macron.
His appearances have recently been accompanied by loud protests and he has accused the government of allowing the campaign to turn into “a climate of quasi civil war”.
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What has he done wrong?
The allegations circling around the Fillon family focus mainly on his Welsh-born wife Penelope.
Le Canard Enchaine alleged she was paid €831,400 (£710,000; $900,000) over several years for working as a parliamentary assistant but reportedly had no parliamentary pass. She was also alleged to have picked up €100,000 for writing a handful of articles for a literary journal.
The family has consistently denied the claims. Initially Mr Fillon said he would stand down as a candidate if his case was placed under formal investigation, but recently he insisted that he would fight on “until victory”.
“The closer we get to the date of the presidential election, the more scandalous it would be to deprive the right and centre of a candidate,” he said.
French election: Francois Fillon faces charges