Saudi Arabia's Prince Alwaleed bin Talal, the billionaire owner of the Savoy hotel in London, has decided to sue Forbes, claiming the magazine has underestimated his fortune by $9.6 billion.
A spokesperson for Forbes said the company was shocked by the Prince's plans to sue, but was sticking by the story.
"We are very surprised at claims that Prince Alwaleed intends to sue Forbes, particularly if he does so in the U.K., a jurisdiction that has nothing whatsoever to do with our recent story, which raised questions about his claims regarding his wealth," said the Forbes spokesperson.
"The Prince's suit would be precisely the kind of libel tourism that the U.K.'s recently-passed libel reform law is intended to thwart. We would anticipate that the London High Court will agree. Forbes stands by its story."
Alwaleed vowed to sever all ties with Forbes in March, after the publication's well-known "Rich List" valued him at $20 billion, and ranked him the 26th wealthiest billionaire on the planet. Alwaleed argued he was worth nearer $30 billion and accused the Forbes list of "intentional biases and inconsistencies".
(Read More: Forbes Hits Back at Saudi Prince Over Rich List)
Forbes said it calculated Alwaleed's fortune based on the underlying value of the investments in his holding company, Kingdom Holding, rather than the price of its shares on the Saudi stock exchange. Through Kingdom Holding, Alwaleed has large stakes in Apple, Twitter, Citigroup and New Corp, and owns a portfolio of luxury hotels, including the Plaza in New York.
—By CNBC's Jenny Cosgrave: Follow her on Twitter