Spain's former king, Juan Carlos I, on Tuesday resumed a UK court battle to win immunity over harassment claims by his former lover, just as a new podcast featuring her claims is released.

Corinna zu Sayn-Wittgenstein-Sayn, 57, is seeking personal injury damages from the 84-year-old royal, who ruled Spain from 1975 until his abdication in 2014.

The British resident has accused Juan Carlos, who now lives in the United Arab Emirates, of spying on and harassing her after their relationship soured in 2012.

She filed a harassment suit in London in 2020, alleging he pressured her to return gifts worth 65 million euros ($65 million), including works of art and jewellery. She is seeking an injunction and damages.

Juan Carlos, listed in court under his full name Juan Carlos Alfonso Victor Maria De Borbon y Borbon, has not appeared at any hearings so far and strenuously denies any wrongdoing.

In March, the High Court in London rejected his claim that a 1978 UK law meant English courts had no jurisdiction to hear the case because he has state immunity as a royal.

Judge Matthew Nicklin ruled that Juan Carlos "was no longer a 'sovereign' or 'head of state' so as to entitle him to personal immunity".

'Agents'

The former king's lawyers appealed and won permission for a legal challenge concerning the period when Juan Carlos was on the throne.

Three judges at the Court of Appeal began hearing legal arguments on Tuesday. A ruling is expected in a few weeks, after which the harassment lawsuit could continue.

Setting out his position, Juan Carlos's lawyer, Tim Otty, argued that immunity is "a procedural bar" and says "nothing about the lawfulness or the morality of the conduct alleged".

However, zu Sayn-Wittgenstein-Sayn's lawyer, James Lewis, argued the appeal should be dismissed, claiming the alleged harassment had involved "intelligence and surveillance" personnel acting as the former king's "agents".

Her lawyers said she received "veiled threats" including a book left in her Swiss flat claiming the "involvement of the British and US intelligence agencies" in the death of princess Diana.

The hearing comes as zu Sayn-Wittgenstein-Sayn, who was also not present in court on Tuesday, has been discussing the relationship in a new podcast series called "Corinna and the King".

Its release has stirred fresh controversy in Spain. Its creators -- two London-based journalists -- defend its timing and independence from zu Sayn-Wittgenstein-Sayn.

"Imagine that someone who says they love your children -- and that you're the love of their life -- would frame you in a criminal investigation," she alleges in the first episode, released Monday.

Shots fired

Court submissions have claimed that Juan Carlos, who is married, was in an "intimate romantic relationship" with the divorcee of a German prince from 2004 to 2009 and showered her with gifts.

Zu Sayn-Wittgenstein-Sayn has alleged that Juan Carlos began harassing her after their relationship broke down.

Juan Carlos "demanded the return of gifts", she claimed, and she suffered "trespass and criminal damage" at her home in rural central England.

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

Her lawyers argued that Juan Carlos had a "more sinister" motive -- transferring money to her from secret bank accounts, on the understanding he could still access it.

The couple's relationship became public knowledge in 2012, when the monarch broke a hip while on holiday in Botswana with zu Sayn-Wittgenstein-Sayn and had to be flown home.

The revelation of the luxury trip, which came at the height of a recession in Spain, sparking public anger there.

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 distanced himself from his father.

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

He and his son attended the state funeral of Queen Elizabeth II in September and were seated together.

Juan Carlos was protected for decades by his huge popularity as a key figure in Spain's transition to democracy following the death of dictator Francisco Franco in 1975.

The excesses of the monarch only came to light in the last years of his reign, triggering a string of investigations over corruption scandals.