London - A mansion on one of London’s most expensive roads is at the center of a legal spat between a widow of the late King Fahd Bin Abdulaziz Al-Saud of Saudi Arabia and a foundation he set up to manage the family’s global assets.

The ownership of Kenstead Hall in the Highgate neighborhood near Hampstead Heath was unlawfully transferred to King Fahd’s widow Al Jawhara bint Ibrahim Al Ibrahim from the Asturion Foundation in 2011, according to lawyers representing the family trust in court documents filed at a London court.

King Fahd died in August 2005 and his legal heirs, including Al Jawhara, inherited control of Asturion. In 2011 the property was transferred to Al Jawhara with the authorization of Faisal Assaly, a member of Asturion’s board, lawyers said in the documents filed in April and released by London’s High Court this week.

“The foundation alleges that the defendant knew or ought to have known that Mr. Assaly was, in signing and implementing the transfer, acting without the authority of the Foundation,” Berwin Leighton Paisner, the law firm representing Asturion, said in the court documents.

A 10-bedroom home on the Bishops Avenue - known as “Billionaires Row" in north London - could sell for as much as 20 million pounds ($30 million), according to Camilla Dell, managing partner of London-based property broker Black Brick Property Solutions.

“It’s the size that makes them sell for so much money,” Dell said by phone. “They are mega mansions. It suits the Middle Eastern way of living, often with servants" and large families.

Kenstead Hall was valued at 28 million pounds in October 2011, according to Land Registry documents. At least three properties are up for sale on the street, priced between 15 and 25 million pounds. Though homes have sold for as much as 2,000 pounds per square feet in the area, demand is waning as even the wealthiest balk at the prices.

"It’s very slow at the moment," Dell said. "There are not a huge number of transactions happening above 2 million pounds after the government raised stamp duty for those homes, and there’s a direct link between London luxury property prices and oil prices."

Lawyers at Berwin Leighton Paisner declined to comment on the suit. Lawyers at Simmons & Simmons, who represent Al Jawhara, didn’t immediately respond to a request for comment. Al Jawhara’s contact details couldn’t be found through an Internet search.

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Jeremy Hodges & Patrick Gower

Saudis spat over $30m mansion