France's far-right National Front has accused authorities of staging a media stunt to influence the presidential election after police searched its headquarters in an investigation into "fake jobs".
The searches on Monday came after French government bond yields rose sharply on news of a poll showing leader Marine Le Pen gaining ground on her main election rivals, independent Emmanuel Macron and conservative former prime minister Francois Fillon.
Le Pen denied on Friday allegations by OLAF, the European Union anti-fraud agency, that she gave parliamentary assistants fake jobs paid for out of EU funds.
French judges opened a fraud investigation on December 15 after prosecutors handed the dossier over to them following a preliminary investigation of more than a year.
"This is as void as space," the party's vice-president Florian Philippot told BFM television, adding searches had taken place a year ago and nothing had been found.
"These are media-stunt searches on the day when (Le Pen) gets a two-point bounce in the polls. It's always when the system is in panic that these affairs come out."
An Opinionway poll of voting intentions on Monday had Le Pen easily beating her four main rivals to win the April 23 first round, with 27 per cent of the vote.
In the second-round two-way run-off against Macron or Fillon, she was still seen losing but she had narrowed the gap in both scenarios.
Fillon's status as favourite to win the presidency in May has evaporated in recent weeks amid questions about what work his wife did for hundreds of thousands of euros in taxpayers' money when she was his assistant.
With nine weeks to go, it is not clear whether Macron or Fillon would go through to the knockout against Le Pen.
Things may become clearer on Wednesday when veteran centrist Francois Bayrou will announce whether he will enter the race.
Bayrou, a pro-EU politician who won 18.5 per cent of first-round votes in the 2007 presidential vote, is polling about five per cent.
