By Gérard Bon
PARIS (Reuters) - France's far-right National Front accused authorities of staging a media stunt on Monday to influence the presidential election after police searched its headquarters in an investigation into "fake jobs".
The searches 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 Dec. 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 that searches had taken place a year ago and nothing had been found then.
"These are media-stunt searches on the day when she (Le Pen) gets a 2-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 percent of the vote.
In the second-round two-way runoff against Macron or Fillon, she was still seen losing, but both scenarios saw her narrowing the gap.
She would lose against Macron with 42 percent to his 58, while against Fillon she would be defeated with 44 percent to his 56, the poll showed. A week ago she was polling around 36-37 against Macron.
It is not clear what impact the probe could have on Le Pen or how quickly the investigation will move forward.
Fillon's status as favorite to win the presidency in May has evaporated in the past three weeks amid questions about what work his wife did for hundreds of thousands of euros in taxpayers' money when she was paid as his assistant.
He has vowed to fight on despite falling ratings and the threat of being placed under formal investigation by the financial police, who are handling the matter.
LEFT-WING BARGAIN UNLIKELY
With nine weeks to go, it is not clear whether Macron or Fillon would go through to the knockout against Le Pen.
The two men are polling at around similar levels, according to several surveys.
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 percent of first-round votes in the 2007 presidential vote, is polling around 5 percent. He has accused Fillon of being under the influence of "financial powers" and said French democracy is under threat.
Macron, whose aides call for a union with Bayrou, is a political novice who has never held elected office. However, he has pulled in huge crowds at rallies, saying he seeks to transcend the classic left-right divide in French politics.
Polls see little chance of a Socialist revival in time for the election given Socialist President Francois Hollande's poor record.
Markets have been uneasy about a possible agreement between hard-left Socialist candidate Benoit Hamon, who is polling at around 15 percent, and independent far-left candidate Jean-Luc Melenchon, at around 12 percent, which could strengthen Le Pen in the second round.
But moves late last week to form an election deal between the two men appeared to have fizzled out.
Melenchon, who is standing as an independent, said: "I have no intention of going and hitching myself to a hearse." Hamon hit back at the weekend, telling journalists: "I won't run after Jean-Luc Melenchon. I don't run after anyone."
(Additional reporting by Simon Carraud, Yann Le Guernigou and Emmanuel Jarry; writing by John Irish and Richard Balmforth; editing by Andrew Roche)