(Yicai Global) July 23 -- Justin Sun, founder of crypto-currency platform TRON, has called of his lunch with Warren Buffett.

The charity event was set for July 25.

Sun cancelled because he is in hospital with kidney stones, he said today on his account on China's Twitter-like Weibo.

The donation is still valid, added the 29-year old tech entrepreneur, who is also chief executive of BitTorrent, an internet-based communication protocol for peer-to-peer file sharing.

Sun, a graduate of the University of Pennsylvania and Beijing's prestigious Peking University, announced on June 4 he had booked the 20th Buffett Charity Lunch for a record USD45,668,800.

The proceeds from the annual auction will go to the San Francisco-based homeless charity the Glide Foundation.

Editor: Ben Armour