A Saudi Prince has launched libel action against against Forbes magazine, accusing them of underestimating his wealth on their annual rich list.

Prince Alwaleed Bin Talal claims the magazine has used flawed methodology to calculate his wealth and has accused Forbes of purposefully leaving him out of the top 10.

The royal, who owns London's Savoy hotel as well as a 3% stake in Twitter, insists they underestimated his fortune by $9.6bn.

prince alwaleed bin talal

Prince Alwaleed Bin Talal of Saudi Arabia

He filed a defamation claim against the Forbes publisher, its editor Randall Lane and two of its journalists, according to court documents seen by the Guardian.

The Saudi Prince claims to be affronted with their calculation because it questioned the sharp rise of his company's stock. He told the Financial Times earlier in May: “You can’t have a magazine say that Saudi Arabia trading is rigged,” he said. “And you can’t also attack Alwaleed bin Talal.”

He reiterated his defence in a Sunday Telegraph interview last month, saying: "They are accusing me of market manipulation. I am not pursuing it because of my wealth, but because they are accusing Saudi Arabia of being manipulated because we have no casinos. This is unacceptable."

Forbes said in a statement: "We're very surprised at claims that Prince Alwaleed has decided to sue Forbes, particularly if he has done so in the United Kingdom, a jurisdiction that has nothing whatsoever to do with our recent story which raised questions about his claims about his wealth.

"The Prince's suit would be precisely the kind of libel tourism that the UK'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."

Prince Alwaleed is listed as having a fortune of $20bn (or £13bn) in the magazine but the Saudi investor claims he actually has more like $29.6bn, beating number ten on the list, French business magnate Bernard Arnault of LVMH with only $29bn.

Mexico's Carlos Slim has remained on top, boasting a net worth of $73bn, or £48bn.