French President Emmanuel Macron stuck by his close ally and speaker of parliament Richard Ferrand on Thursday after he was charged with conflict of interest over a property deal involving his wife.

The allegations against Ferrand first emerged in 2017, causing embarrassment for Macron who had just won power on a pledge to rejuvenate France's corruption-plagued political class.

Ferrand, who had been appointed a minister in Macron's first cabinet, stepped down at the time, but later made a comeback as speaker after prosecutors dropped the case, saying there was no basis for a prosecution.

The matter did not end there, however.

In 2018, an anti-corruption organisation filed another complaint against Ferrand, forcing magistrates to re-examine the property deal in 2011 between a public health insurance fund he was managing and his wife in his native region of Brittany.

Macron still has "all his confidence" in Ferrand, government spokeswoman Sibeth Ndiaye said Thursday, dismissing calls for the 57-year-old to step down from his role chairing the National Assembly.

After the charges were filed by a magistrate in the northern city of Lille on Wednesday evening, Ndiaye described the former Socialist MP as a "loyal, upstanding man with an exemplary political career."

Being charged, or "mise en examen", in France means investigating magistrates believe there is strong evidence against an individual but the decision can be appealed and it does not necessarily mean the case will go to trial.

- Blow for Macron -

The allegations against Ferrand, one of Macron's first backers when he ran for president, were revealed by the Canard Enchaine investigative weekly in 2017.

The charges come just as Macron is regaining popularity following months of "yellow vest" protests, with the head of state keen to show a more humble side.

The Canard Enchaine revealed that in 2011 a public insurance fund that Ferrand headed had agreed to rent a commercial building from Ferrand's wife and also invest 184,000 euros ($202,000) in renovations.

The work carried out drastically increased the value of the property.

Ferrand denied any wrongdoing, saying that his wife had made the best offer and that he had no say in the matter.

In a statement sent to AFP Thursday, Ferrand said he was "determined to continue (his) role" as president of the lower house of parliament, which he has held since September 2018.

He said he was "serene about the outcome of the investigation", arguing that no new evidence had been brought forward since 2017 in the case, "in which there is neither harm caused nor victim."

The charges come as another key ally of Macron's is under scrutiny amid a series of investigations over suspected fake jobs in the European Parliament.

Francois Bayrou, head of the centrist MoDem party which is allied to Macron's Republic on the Move party, was questioned on Wednesday by anti-corruption police over claims that MoDem misused EU money for parliamentary assistants.

Marielle de Sarnez, a MP who briefly served as European Affairs minister in 2017, was also questioned.

A day earlier, France's pick for the European Commission, Sylvie Goulard, was also questioned by police over the claims involving her former MoDem party.

Members of the far-right National Rally (ex-National Front), including its leader Marine Le Pen, are also being investigated over similar allegations.

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