French prosecutors are investigating a Nazi-themed stag party attended by the Conservative MP Aidan Burley.
Mr Burley lost parliamentary private secretary post after he was photographed at a stag party in the Alps with a man wearing Nazi costume.
"A preliminary investigation started yesterday," Paris prosecutor Patrick Quincy told AFP.
However there is no criminal investigation into Mr Burley's actions, according to Paris prosecutors.
Mr Burley said: "They are launching a preliminary investigation and I understand I am not the focus of it.
"I do not believe I have broken any French law and have distanced myself from the behaviour of other people on the stag."
The MP for Cannock in Staffordshire has previously apologised for the "inappropriate behaviour" of fellow guests at the stag party.
He said he had not been contacted by the French authorities.
It is thought the investigation has been triggered by a complaint to the prosecutor from French anti-racism group SOS Racisme.
In a statement on Thursday, Mr Burley said: "Being involved in a stag party where an SS uniform was worn was wrong and offensive.
"It was the wrong decision on my part; crass and insensitive.
"I am deeply sorry, and want to take this opportunity to offer the people of Cannock Chase an unreserved, wholehearted and full apology for the terrible offence this incident has undoubtedly caused.
"It has been an unbelievably difficult 10 days for my family and friends, and I feel ashamed that Cannock Chase has been placed in the limelight as a result of my behaviour.
"My family have been through hell, and I want to thank them in particular for the love, courage and support they have given me."
Ian Austin, shadow work and pensions minister and Labour MP for Dudley North, said: "David Cameron and the Tories tried to brush this under the carpet, but the scandal surrounding Aidan Burley's disgraceful conduct is not going away.
"Surely the prime minister must take the whip off Mr Burley while this investigation is taking place."
Mr Cameron has ordered an inquiry but it is understood it is unlikely to conclude before the new year.
A Downing Street spokesman declined to comment about the decision by the French authorities to investigate the stag party but reiterated that Mr Burley's conduct had been "offensive and foolish".
Possible charges under French law that could stem from wearing Nazi uniforms include incitement to racial hatred and being an apologist for Nazi war crimes.
Under French law prosecutors are obliged to follow up complaints that allege criminal wrongdoing. A preliminary investigation is then launched to ascertain whether any crimes have been committed.
A preliminary investigation is not a criminal investigation but if it is decided a crime has been committed a formal judicial investigation will be launched which could include the naming of suspects.