HAVANA - Cuban President Fidel Castro furiously denied on Monday a story in Forbes magazine that he was worth $900 million and said he would step down if the magazine could prove the assertion.

Cuban President Fidel Castro displays a copy of Forbes magazine, which had ranked him as the seventh wealthiest ruler in the world, during a live television broadcast in Havana, May 15, 2006. [Reuters]

The financial magazine ranked Castro as the seventh wealthiest ruler in the world in its annual tally of the "Fortunes of Kings, Queens and Dictators."

Castro went on television brandishing a copy of the US-based magazine to tell Cubans the story was a "repugnant slander" by a capitalist publication.

With Communist Cuba's Central Bank governor at his side, Castro challenged Forbes to prove the allegation.

"If they can prove that I have a bank account abroad, with $900 million, with $1 million, $500,000, $100,000 or $1 in it, I will resign," he said at the end of a four-hour broadcast.

"It is so ridiculous to say I have a fortune of $900 million, a fortune with no heirs. What would I need all that money for, if I will soon be 80 years old?

Castro, in power since a leftist revolution in 1959, says his net worth is nil and that he earns only 900 Cuban pesos ($40) a month.

Kings and sheiks of the oil-rich Gulf Arab states still top the Forbes list, published in its May 22 edition.

Castro ranked higher than Queen Elizabeth of Great Britain, whose fortune according to the Forbes amounts to some $500 million in estates, gems and a stamp collection built by her grandfather, but not Buckingham Palace or the crown jewels. The British monarch came to the throne in 1952, seven years before Castro seized power.

Castro last year threatened to sue Forbes after the magazine included him on its 2005 list with an estimated fortune of $550 million.

The Forbes estimate includes state enterprises that the magazine assumes he controls in Cuba, among them the Havana Convention Center, the Cimex retail conglomerate and a pharmaceutical company that exports vaccines.

Forbes said it assumed a portion of the profits of state companies goes to Castro and cited rumors of money stashed in Swiss bank accounts, but gave no details, saying former Cuban officials insist Castro has skimmed profits for years.