PARIS France's ambassador to Japan has pledged not to serve under far-right leader Marine Le Pen if she becomes president, saying her policies are at odds with French principles.
Thierry Dana, writing in Le Monde newspaper, became the first high-ranking French diplomat to state publicly that he would step down rather than work for Le Pen if she were to win presidential elections held over two rounds in April and May.
"If the pieces of the French tragedy which are being put in place were to lead to her election, I would stand aside from any diplomatic role," Dana said.
"I couldn't loyally defend your positions, which run counter to all the principles championed by France when it is great in the world," he wrote.
Buoyed by the election of President Donald Trump in the United States and by Britons' vote to leave the European Union, Le Pen's anti-immigration, anti-EU National Front hopes for similar populist momentum in the French election.
Outgoing President Francois Hollande also warned ministers at a cabinet meeting on Wednesday about the threat posed by the extreme right, especially to France's role in the European Union, government spokesman Stephane Le Foll said.
Most polls show Le Pen winning the first round but losing heavily in the second, whether she is pitted against independent centrist Emmanuel Macron or conservative Francois Fillon.
However, Fillon's legal woes over allegations of misuse of public money have increased investors' concerns that Le Pen could win and take France out of the euro and the EU.
Japanese investors were net sellers of French bonds for the third month in a row in January, the longest such spell since mid-2011, due to uncertainty over the French elections, Japanese Ministry of Finance data showed on Wednesday.
Dana, 60, said he was due to take up a new diplomatic post in the summer, but he would rather give it up than "serve the diplomacy of the National Front".
"When you claim to restore our grandeur, you are shutting France in a cellar filled with demons that we thought had been forgotten," he said.
National Front deputy leader Florian Philippot responded on Twitter: "Go ahead and resign then. No problem."
Dana won praise from France's ambassador to the United States, Gerard Araud, who said on Twitter "very nice article from my counterpart in Tokyo".
In response to Dana's article, Foreign Minister Jean-Marc Ayrault sent a message telling all French diplomats that they must remain neutral during the election.
However, he echoed some of the worries raised by Dana, saying "in all my contacts with foreign partners, I note every day the concern that the preparation of our election day is causing."
"Our partners want France to remain France, a country open to the world and committed to a more united Europe," Ayrault said in the note seen by Reuters.
(Reporting by Adrian Croft, Jean-Baptiste Vey, Marine Pennetier; Editing by Mark Trevelyan)