A picture of a mentally challenged blind man, chained to a tree by his own father, has left thousands of people outraged in China.

A Mail Online report, which carries the picture of a naked Cheng Xiangtao sitting outside a cave with a bowl of food in his hand, says that Xiantao's father has been forced to turn his disabled 26-year-old son into a caveman because of his poor financial condition.

Cheng Xiangtao was born blind and mentally disabled. After their family home was lost, his father, 70-year-old Cheng Yuanchao apparently had no other option but to leave his son chained by the ankle to a cave in remote Chengling village of Henan province.

However, Xiangtao himself lives with his daughters.

"I have no home of my own now and nowhere to house my son. This is the best I can do. I visit him three times a day with food and water so he is never hungry or thirsty," Yuanchao said.

"The chain is there only so he doesn't run off and hurt himself."

Yuanchao said: "I'm not a wealthy man and we've never been able to afford doctors who might have been able to help him."

The disturbing pictures have shocked people around the world .