Juan Carlos abdicated in 2014
Lawyers for Spain's former king Juan Carlos I argued he had immunity from English courts. He abdicated in 2014. AFP

A UK judge on Friday ruled that the former lover of Spain's former king Juan Carlos I cannot bring a claim of harassment against him in the courts in London.

Danish businesswoman Corinna zu Sayn-Wittgenstein-Sayn, who is in her late 50s and lives in England, sued Juan Carlos, 85, who abdicated in 2014, for damages of more than GBP126 million ($154 million) for personal injury.

She alleged that he caused her "great mental pain" by spying on and harassing her.

"The High Court of England and Wales lacks jurisdiction to try this claim," judge Rowena Collins Rice said in a written judgment on the civil case brought by zu Sayn-Wittgenstein-Sayn.

"I was shown no authority coming anywhere near supporting an assumption of English jurisdiction over a foreign-domiciled defendant in such circumstances," Collins Rice added.

At the same time, "she has not sufficiently established that the 'harmful event' of which she complains -- harassment by the defendant -- happened in England", the judge ruled.

The judge recognised zu Sayn-Wittgenstein-Sayn "has an account she wishes to give of her personal and financial history with the defendant, and about the harm he has caused her peace of mind and personal wellbeing, and her business, social and family life".

However, she added: "The only question for me has been whether the claimant can compel the defendant to give his side of the story to the High Court. My conclusion, as things stand, is that she cannot."

Responding to the ruling, Zu Sayn-Wittgenstein-Sayn said she was "deeply disappointed" and that it was "disheartening to see that victims of harassment often struggle to find justice in our legal system".

She added: "Intimidation and harassment of me and my children continues and is aimed at fully collapsing me.

"Juan Carlos has deployed his full armoury to grind me down and the reach of his power is immense.

"I am considering all options," she added.

Juan Carlos, who is married, was in an "intimate romantic relationship" with the divorcee from 2004 to 2009 and showered her with gifts, according to previous court submissions.

Zu Sayn-Wittgenstein-Sayn alleged that Juan Carlos began harassing her after their relationship broke down, using threats, break-ins at her properties and surveillance.

Gunshots damaged security cameras at the front gate of her property, she alleged, accusing the former king of being angry at her refusals.

The couple's relationship became known in 2012, when the monarch broke a hip while on holiday in Botswana with Zu Sayn-Wittgenstein-Sayn and had to be flown home, sparking public anger during a period of record unemployment in Spain.

Two years later, dogged by scandals and health problems, Juan Carlos abdicated at the age of 76 in favour of his son, Felipe VI, who has now publicly distanced himself from his father.

He went into self-imposed exile in the United Arab Emirates in 2020.

Three appeal judges in London in December ruled his ex-lover could not sue him for harassment in the English courts for the period while he was on the throne as he had immunity as sovereign.

But they left open the possibility that she could pursue him for his alleged behaviour after his abdication.