Investigative website Disclose published a series of articles in 2021, including one in which it alleged that the Egyptian state used a French counter-intelligence operation in Egypt, codenamed "Sirli", for a "campaign of arbitrary executions" against smugglers on the Libyan border.

The journalist who wrote the articles, Ariane Lavrilleux, was however not to be tried as her article was deemed of "public interest", the source said.

Prosecutors had in August urged the military member be tried for the lesser charge of "breach of professional confidentiality", but the investigating magistrate on October 9 ordered he go to court in May next year charged with "leaking defence secrets", it added.

The Paris prosecutor's office confirmed the trial had been ordered, but it said that it had on Monday appealed the magistrate's decision to try him on the more serious charge.

The engineer has denied any wrongdoing.

His lawyer, Margaux van der Have, dismissed the charges, saying the accusation was not based on any "established facts", but rather the "probability" of a leak.

Lavrilleux was arrested in 2023, sparking outrage among fellow journalists and raising questions about how the government employs controversial laws on issues of national secrecy, in a country that is supposed to cherish the right to freedom of expression.

She spent 39 hours in detention, repeatedly interrogated by domestic intelligence agents for simply, she said at the time, doing her job.

Amnesty International secretary general Agnes Callamard at the time described the arrest as "chilling" and described it as part "of a wider attack on public interest journalists who attempt to expose the opaque actions of the French intelligence services."

"If we don't protect sources, it's the end of journalism," Lavrilleux said.