Pippa Middleton’s father-in-law has been placed under formal investigation over the suspected rape of a minor.

David Matthews, 74, a multimillionaire hotel owner, was arrested on Tuesday (French time) by the Juvenile Protection Brigade and formally put under investigation for suspected rape of a minor under his authority, news service Reuters reported, citing a court source.

A spokesman for Mr Matthews told UK newspaper The Telegraph that he “categorically denies the allegation and unequivocally contests the untrue and scandalous accusation”.

Paris prosecutors arrested Mr Matthews during a visit to France. They later released him and placed him under judicial control, the source told Reuters.

The source did not say when he was released. French police can hold suspects up to 48 hours in such cases.

The source said the alleged rape took place in 1998-99. Radio network Europe 1 reported that a complaint was filed in 2017.

Pippa’s stunning gown almost stole the show at sister Catherine’s wedding to Prince William. Photo: Getty

Being placed under judicial control means prosecutors have attached certain conditions to his release, most likely including limits on who he can meet and where he can go. The source did not tell Reuters what specific conditions were attached in Mr Matthews’ case.

Mr Matthews is the father of James Matthews, who married Ms Middleton in May 2017. Ms Middleton first came to global attention in 2011 because of the eye-catching white dress she wore as maid of honour at the wedding of her sister, Princess Kate.

Ms Middleton’s own lavish wedding to James Matthews last May was one of the most widely reported social events of the year, attended by William and his brother Harry, grandsons of Queen Elizabeth.

Mr Matthews is a former racing driver who ventured into car sales and then hotels after a horrific crash ended his racing career in 1973.

Sealed with a kiss: Pippa Middleton and James Matthews in 2017. Photo: Getty

In France, complex criminal cases are handled by special magistrates with broad investigative powers. They place defendants under formal investigation when enough initial evidence of serious wrongdoing has been found.

Magistrates can either drop cases they believe have insufficient evidence to warrant going to court or summon defendants to stand trial.

The maximum sentence for rape in France is 15 years in prison, or up to 20 years if the victim was under 15.

-with AAP