A Saudi billionaire has announced one of the biggest philanthropic gestures in history, promising to donate all his $32bn (20bn) wealth to charity over the coming years. Prince Alwaleed bin Talal, a 60-year-old magnate who is a nephew of the late King Abdullah, said he would channel the money through his own Alwaleed Philanthropies organisation. The money will go to programmes promoting health, eradicating disease, modernisation, intercultural understanding and empowering women, he said. "This donation will be allocated according to a well-devised plan throughout the coming years," the prince said in a statement. "Philanthropy is a personal responsibility, which I embarked upon more than three decades ago and is an intrinsic part of my Islamic faith. With this pledge, I am honouring my life-long commitment to what matters most - helping to build a more peaceful, equitable and sustainable world for generations to come." The prince's move will be modelled on the Bill and Melinda Gates foundation, which last year donated $4bn to various causes. Gates said Alwaleed's decision "is an inspiration to all of us working in philanthropy around the world." Gates, who set up his foundation in 2000, has signed up more than 100 billionaires, including Mark Zuckerberg, Michael Bloomberg, Richard Branson and George Lucas, to giving away half their fortunes to charity.