Shanghai: A disturbing video of two 12-year-old boys fighting in a mixed martial arts cage in China has sparked impassioned online debate over the plight of orphans in the country.

An MMA club in the southwestern city of Chengdu has adopted hundreds of boys who lost their parents at a young age, raising and training them as fighters, according to reports.

In shocking footage from a short documentary by Chinese private streaming website Pear Video circulating widely on social media, two pre-teens are seen taking part in a bruising fight in an octagonal steel cage.

One knocks the other down and proceeds to bash him repeatedly about the head and body as the losing fighter cowers on the mat.

Models wearing bikini tops and short jeans cheer and a man with a microphone whips up the crowd by saying the boys were “fighting for their fate”.

A local-level office of the Ministry of Civil Affairs, which handles orphans in China, brought most of the children to the En Bo Fight Club, its founder told the makers of the documentary.

Most of the children in the club were from China’s dozens of minority groups, including Tibetans.

The Beijing News, a state-run newspaper, accused the club of exploiting the children.

“Did they enjoy the right to education based on the law while they underwent strict training and competed in intense fights?” an editorial asked on Friday.

The issue also was a point of fierce debate on China’s Twitter-like Weibo platform.

“Soliciting and using minors to engage in commercial performances which are also violent, while depriving them of a salary, is illegal,” wrote one user named Chen Ming.

Others argued that without the club the boys would end up on the street and a possible life of crime.

A 14-year-old boy named Xiaolong says in the documentary that he is happy to be safe and well fed.

“There is everything here — food, clothes and a place to live. The food here is much better (than at home). There is beef and eggs but I can only have potatoes at home.”

China had 500,000 orphans at the end of 2015, with less than 20 percent raised by the state and only about five percent adopted, the latest-available official figures show.

The fate of the rest is unclear.

Five little boys living on the street were found dead in a rubbish bin in southwestern Guizhou province in 2012 when they lit a fire in the bin to stay warm.