PARIS (AFP) - The disgraced former bodyguard of French President Emmanuel Macron admitted Sunday (Dec 30) he had used his diplomatic passports "for personal convenience" after being fired in August, a day after investigators opened a probe into his failure to return the documents.

Alexandre Benalla, a former campaign bodyguard who got a senior job following Macron's election victory last year, has been dogged by scandal since July when accusations emerged he had roughed up protestors.

Macron's office and Benalla clashed this week over accusations that he used two diplomatic passports after his dismissal, which the foreign ministry said would be a crime.

Criticism over the presidency's handling of the issue has been growing since local media reported Benalla met with African presidents, in what officials fear was an attempt to profit from his former insider status.

In an interview published Sunday, Benalla acknowledged using the passports for private travel but said he would return them to the foreign ministry "within days".

"I may have been wrong to use these passports," he told French newspaper Le Journal du Dimanche.

"But I did it for personal convenience to facilitate my passage through airports. Under no circumstances did I used them for business." Benalla said he had returned the passports at the end of August but added that they were handed back to him along with other personal belongings by a "presidential aide" in October.

"Insofar as they were given back to me, I didn't see any reason not to use them," he told the paper.

Prosecutors on Saturday opened a preliminary investigation for "abuse of trust", the illegal use of professional documents and other charges.

Macron's office said this week it had no information about the use of Benalla's passports, which it said were assigned only for work in his official capacity.

Benalla was at the centre of a major scandal this summer after accusations emerged he had beaten up demonstrators at a May Day rally in Paris while he was wearing a police helmet. He was working for the presidency at the time.

He was not fired until after the media revelations, prompting a wave of accusations from government opponents that Macron's office covered it up.

Benalla has denied boasting of insider influence to win work after his sacking and has accused members of Macron's entourage of trying to "wreck" his life.