Saudi tycoon Prince Alwaleed bin Talal has promised his entire $US32 billion ($41.8 billion) fortune to charitable projects in coming years in one of the biggest ever such pledges.

The pledge was potentially the “first such big announcement” of its kind in the region, and is modelled on a charity established by Microsoft founder Bill Gates in the United States, the prince told reporters.

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Prince Alwaleed said his charity “will help build bridges to foster cultural understanding, develop communities, empower women, enable youth, provide vital disaster relief and create a more tolerant and accepting world”.

The money “will be allocated according to a well-devised plan throughout the coming years”, he said, but stressed there was no time limit for the donation to be spent.

He said he would head a board of trustees tasked with spending the funds which would still be used after his death “for humanitarian projects and initiatives”.

The 60-year-old magnate belongs to the Saudi royal family and is a nephew of king Abdullah, who died on January 23.

In the conservative Muslim kingdom, Prince Alwaleed, who holds no government rank, is unusual for his high profile and periodic comments about economic issues.

He is the owner of Kingdom Holding, which has interests ranging from the media to the Euro Disney theme park and the Four Seasons hotels and Citigroup.

Prince Alwaleed’s recent pledge to leave his fortune to charitable projects in coming years joins those other generous billionaires have made in the past.

The prince is constructing a tower in the Red Sea city of Jeddah that is to rise more than one kilometre to be the world’s tallest building.

Earlier this year, he opened a pan-Arab news channel in Bahrain but authorities there shut the station after less than 24 hours and a new home is being sought.

Prince Alwaleed told reporters he had already donated a total of $US3.5 billion over more than 35 years through his Alwaleed Philanthropies.

The charity has distributed houses and provided electricity to isolated Saudi communities, while supporting other projects around the world.

He said he announced his pledge now, after years of preparation, to institutionalise the process “so they can continue after my lifetime”.

Flanked by his son Prince Khaled and daughter Princess Reem, he said they would be president and vice-president of the charity after he died.

“I believe that a person should take dramatic and drastic decisions at his peak,” Prince Alwaleed said, proclaiming himself to be in good shape.

“I’m very healthy, enough to bike every day three hours,” he said. “I assure you my health is good.”