LOS ANGELES • Young players have been physically abused and left without schooling at National Basketball Association (NBA) academies in China, which were described as "sweat camp(s) for athletes", an ESPN report said.

Multiple American coaches have complained about physical punishment at the academies including a facility in Xinjiang, the region where China is accused of holding more than a million members of ethnic minorities in internment camps. The NBA said it cut ties last year with Xinjiang, but continues to operate academies in Shandong and Zhejiang provinces, in facilities run by the Chinese government.

One former coach said he saw a Chinese counterpart hurl a ball into a young player's face and "kick him in the gut" according to the ESPN investigation.

"Imagine you have a kid who's 13, 14 years old, and you've got a grown coach who is 40 years old hitting your kid," the coach was quoted as saying. "We're part of that. The NBA is part of that."

NBA deputy commissioner Mark Tatum told ESPN only a "handful" of complaints about abuse had been received and officials in the league's New York office, including commissioner Adam Silver, were not aware of broad mistreatment of players.

He added the league is "re-evaluating" the academy programme.

According to the NBA Academy website, players in these academies range from 14-18 years old.

"One of the lessons we've learned here is that we do need to have more direct oversight and the ability to make staffing changes when appropriate," Tatum said.

"We don't have oversight of the local coaches, of the academic programmes or the living conditions. It's fair to say we were less involved than we wanted to be."

The report comes at a time of fraught relations between the NBA and China. State broadcaster CCTV stopped screening NBA games last year after Houston Rockets general manager Daryl Morey tweeted in support of pro-democracy protesters in Hong Kong.

The NBA began launching international academies in 2016, placing three in China with the aim to unearth the next Yao Ming, the towering former Rockets centre. But the Chinese project was "fundamentally flawed" according to Bruce Palmer, a former technical director at a private basketball school in China who was hired by the NBA to evaluate the academies.

The main problems were that NBA employees were placed under Chinese authority, and the league was prevented from working with China's elite players, Palmer said.

According to ESPN, one coach requested a transfer after seeing Chinese coaches hit teenage players, while another left because he could not stomach the lack of education.

Education was intended as a central plank of the academies, but no formal schooling was provided by the Chinese sport bureaus, the report said. It detailed cramped living conditions at the Xinjiang academy, where rooms meant for two players were accommodating up to 10, sleeping in bunk beds.

Players trained two or three times a day, ESPN said, adding that teenagers as young as 13 were often left unsupervised.

AGENCE FRANCE-PRESSE