A Qatari prince’s ex-wife has been found dead in Spain – after she claimed her former husband inappropriately touched a child.

The body of Kasia Gallanio, the third wife of billionaire Abdelaziz bin Khalifa Al Thani, 73, was found in her home in Marbella, Spain, The Sun reports.

Ms Gallanio was 45 at the time of her death, and had been going through a bitter custody battle with her ex, the uncle of the current Emir of Qatar.

A former princess of Qatar has been found dead in her Marbella home aged 45 amid an ugly custody battle with her ex-husband. Picture: Instagram/@kashounia

During the custody battle, she had claimed her ex-husband – the former oil and finance minister for Qatar – had touched a minor in an inappropriate way.

He vehemently denies the allegation.

Spanish police discovered Ms Gallanio’s body in a bed on Sunday morning.

According to Spanish newspaper El Pais, she was found after her youngest daughter, who lives in Paris, told police she’d been unable to contact her mum for days.

Kasia Gallanio was the third wife of billionaire Abdelaziz bin Khalifa Al Thani. Picture: Getty

Le Parisien reports that a Paris court had dismissed her custody demands just days ago, on May 19.

The case was postponed pending a psychological evaluation after Ms Gallanio was hospitalised with a “breakdown”, it’s alleged.

The former couple shared 17-year-old twins who initially lived with Al Thani before they decided to move in with their mother in Marbella.

She had alleged her ex decided to “cut them off” as “punishment”.

Police say the cause of her death is believed to be a drug overdose. Picture: Instagram/@kashounia

Their third daughter, 15, lives with the Qatari royal in Paris, where he was exiled after a coup in 1995.

They have been in an ugly legal battle for 15 years over the custody of their children.

Courts heard Al Thani accused his former wife of being an “alcoholic”, while she in turn accused him of abuse.

In a recent interview with Women’s World, Ms Gallanio said: “The little one is not allowed to talk to me which makes me extremely sad because she gets a lot of material things from her father so it’s almost like manipulation and blackmail.

Ms Gallanio and her ex had been fighting a bitter custody battle over their three daughters. Picture: Instagram/@kashounia

“It’s like a part of my body is missing.”

Speaking to Olive Press, a Spanish English-language newspaper, a close friend of Ms Gallanio described her as a “good person”.

“I knew her very, very well and am devastated at the news,” Louis Spagnuolo told the publication. “She was a very good person and those who knew her loved her.”

Allegations against Al Thani emerged during a recent court hearing in Paris.

A post-mortem will be held to establish the cause of Ms Gallanio’s death.