European stocks extended losses and the single currency fell after France's Alain Juppe said he would not run as a late-entry candidate in the country's upcoming Presidential elections, leaving the race to his embattled center-right colleague Francois Fillon.

Juppe, 71, who lost in a party-political run-off to Fillon last year, told reporters in Bordeaux that it was "too late" to enter the campaign, despite the flagging support for the scandal-hit Fillon. Had Juppe opted to run, polls indicate he would have easily gained enough support to make it to the second round and would have likely eliminated far-right challenger Marine Le Pen.

However, with anti-European Le Pen now firmly in the frame to at least win enough support on April 23 to advance to the second stage, and Fillon facing the prospect of formal charges from French authorities with respect to allegations he paid family members hundreds of thousands of euros to perform so-called "fake jobs", investors trimmed risky bets in and around Europe's second-largest economy.

The euro fell more than 0.33% against at a weaker U.S. dollar to change hands at 106.02 by 14:25 GMT while benchmark 10-year French government bonds, known as OATs, were marked 3 basis points higher at 0.98% before paring the rise to around 0.96%.

Concerns that Le Pen could spring an unlikely victory that could lead to the unravelling of the Eurozone have kept markets on edge for several weeks, and the odds of that lengthened Friday after a new poll predicted Le Pen would finish second in the first round, behind independent candidate Emmanuel Macron.

The crisis in French politics was such that former President Nicolas Sarkozy took to Twitter early Monday to seek a "dignified and credible way out from a situation which cannot last any longer and which is the source of deep concerns among French people."

Fillon vowed to fight on in the election at a rally Sunday in Paris even as polls showed him likely to lose the first round vote on April 23, leaving the May 7 run-off to Macron and Le Pen.

"I see no reason to [drop out]," Fillon told France 2 television. "It would lead to a dead end for my political family."

"I am not autistic," he said. "I want to convince my friends that my programme is the only one that can bring about recovery for the country."