[PARIS] French rightwing presidential candidate Francois Fillon on Monday apologised for hiring his wife as his parliamentary aide, admitting he made an "error" as he sought to draw a line under a damaging scandal.

Fillon's bid has been in turmoil since it emerged that his British-born spouse was paid handsome sums for a suspected fake job as a parliamentary assistant.

Late Monday, the candidate himself corrected a version first leaked in the press, revealing that the after-tax payments to his wife totalled more than 680,000 euros (S$1.03 million) over a total of 15 and a half years starting in 1986.

Mr Fillon also used funds available to lawmakers to hire two of his children, paying them 84,000 euros pre-tax between 2005 and 2007.

"It was an error, I profoundly regret it and I apologise to the French people," Mr Fillon told a press conference while insisting he had done nothing illegal and that his wife Penelope's earnings were justified.

The former prime minister, 62, said he had hired family members - as allowed in France - out of "trust" but now recognised that such policies "create distrust nowadays".

Rejecting calls from some within his camp to step aside, he declared: "From tonight, I announce here that it's a new campaign that's starting." "I am a candidate for the presidency to win it," he added.

Mr Fillon's press conference was seen as crucial to his chances after a flurry of allegations that have tarnished his sleaze-free image and triggered a preliminary probe into possible misuse of public funds.

France goes to the polls in April and May for a two-round presidential election.

Mr Fillon, a devout Catholic who won the nomination of the Republicans party in November on a pledge to slash public spending, had been the frontrunner until two weeks ago.

Polls now show him possibly crashing out in the first round, likely leaving far-right candidate Marine Le Pen and rising star Emmanuel Macron, a centrist, to battle it out in May's runoff vote.

Mr Fillon again presented himself as the victim of dirty tricks on Monday, claiming "32 years of irreproachable ethics" in politics.

Addressing allegations that Penelope did not actually perform the duties for which she was paid, he said: "No one has the right to judge what a parliamentary assistant's job consists of, except the MP himself."

In an interview in 2007, which was unearthed by French reporters last week, Penelope said she had "never been actually his assistant or anything like that." Fillon said this was "taken out of context" - a claim denied by the journalist - and that his wife had worked constantly in his central Sarthe constituency managing his mail and local meetings.

Her average monthly salary of 3,677 euros was "perfectly justified", he said.

The candidate cast blame on the press for exposing the affair, saying he was a victim of a "media lynching" and suggesting it was designed "to benefit those who don't want the right to win".

Both Mr Fillon and his wife were questioned last week over the affair.

Penelope told investigators her parliamentary work had been mainly informal, Le Monde reported Monday.

When working between 2002 and 2005 for Mr Fillon's replacement in parliament she had "never taken notes", the paper quoted her as saying.

The investigation is also looking into payments she received from a literary magazine owned by a friend of her husband.

Le Monde said investigators were looking at whether she was paid around 5,000 euros a month pre-tax between May 2012 and December 2013 in return for the magazine's editor being recommended by Fillon for France's highest honour, the Grand Cross of the Legion of Honour, in 2010.

In a statement to AFP, the magazine's owner Marc Ladreit de Lacharriere denied any link and said Penelope's work "was in no way fictious".

The scandal risks adding to the anti-establishment sentiment that fuelled Brexit and Donald Trump's rise to the White House.

Mr Fillon's listing poll numbers had created alarm in his camp, leading some members of his party to call for a replacement candidate.

Republicans lawmaker Jacques-Alain Benisti said on Monday said he believed Mr Fillon's explanations would mend the rift.

"The dissenters will now fall in line," he said.

Mael Pouliquen, an 18-year-old economy student who has campaigned for Mr Fillon before the scandal, said he found the politician "very frank and very clear." "He has my support again, for now anyway," he told AFP.

Some of Fillon's party critics had suggested 71-year-old Alain Juppe, the runner-up in the Republicans primary, should take over. He ruled this out again on Monday.

AFP