Story highlights Lawyers for François Fillon say the inquiry violates the prosecutor's rules of conduct

Fillon has rejected claims his wife and children were paid for work they didn't do

Paris (CNN) France's financial prosecutor said Thursday that its investigation into presidential candidate François Fillon will remain open, in what must be another blow to a campaign dogged by allegations of corruption.

Fillon, chosen in November as the Republican party candidate for the presidency, has previously rejected the claims, declaring he has "nothing to hide."

It is alleged that Fillon's wife, Penelope, and children have received public funds for work they did not do.

In a statement, the financial prosecutor's office said it had received the results Wednesday of a preliminary investigation into the allegations of embezzlement of public funds.

"Many elements are already collected and the case cannot be dropped at this moment," the statement said.

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