French conservative presidential candidate Francois Fillon has denied that he acted illegally in a scandal surrounding his wife's well-paid job as his assistant.
Mr Fillon told a news conference on Monday that "all acts evoked (in the press) are legal and transparent."
He said "I have nothing to hide" and the accusations are "unfounded" and that he would publish details of his assets on the internet on Monday.
He said he would not withdraw from the race, but apologised to the French people for employing his wife, saying that giving work to your family is a practice that is now rejected.
Mr Fillon, a Thatcherite free-marketeer who vows to overhaul France's heavily regulated economy, has come under mounting pressure to step down since the scandal broke last month when the investigative weekly le Canard Enchainé published the allegations.
The paper claimed Penelope Fillon had been paid more than €800,000 euros (£690,000) over a decade as a parliamentary aide to her husband but had in fact did little or no work.
Opinion polls show that more than two thirds of French people want Mr Fillon to pull out of the race, and a growing number of politicians in his own Les Républicains party have said he must go or risk losing the election for them or even splitting the party.
The scandal has been a humiliating reversal of fortune for the former prime minister, a devout Catholic who pitched himself to the electorate as an honest and irreproachable candidate but who is now being investigated for possible misuse of public funds.
Until the allegations emerged he had been favourite to win the presidential election, but polls now predict he will come third in the first round on April 23.
The far-Right leader Marine Le Pen is tipped to come first and centrist Emmanuel Macron second, and the pair would then go through to the run-off two weeks later which Mr Macron would comfortably win.
Since the scandal broke, Mr Fillon and his Welsh-born wife have been interviewed by financial prosecutors, his office in parliament has been searched, and the investigation has been extended to two of his grown-up children.
Le Monde newspaper reported on Monday that investigators were now also probing whether Mr Fillon awarded the highest French state honour - the Grand Croix de la Légion d'Honneur - to the wealthy owner of a literary review in return for giving his wife a well-paid sinecure.