China on Tuesday pulled NBA exhibition games from television screens as the league faced an escalating punishment campaign in the lucrative Chinese market ignited by an American basketball executive’s pro-democracy tweet.

However the National Basketball Association faced a counter-attack in the United States, where presidential candidates and influential senators accused it of kowtowing to authoritarian China.

The crisis erupted Friday when Houston Rockets general manager Daryl Morey tweeted support for protesters in the semi-autonomous southern Chinese city of Hong Kong who are demanding greater freedoms.

The NBA, seeking to balance its interests in the Chinese market against American free speech values, found itself being smashed by both sides in a reflection of the broader tensions between the global superpowers.

The league intially put out statements that senior US politicians slammed as bowing to China for financial reasons, while Rockets star guard James Harden apologised.

But NBA Commissioner Adam Silver on Monday insisted his organisation supported Morey’s right to express his opinions.

The Chinese state-run broadcaster responded on Tuesday, announcing it had shelved plans to broadcast a pair of pre-season exhibition games to be held in China this week and was considering more punishments.

“We believe that any comments that challenge national sovereignty and social stability are not within the scope of freedom of speech,” China Central Television (CCTV) said on its social media account.

“To this end, CCTV’s Sports Channel has decided to immediately suspend plans to broadcast the NBA preseason (China Games) and will immediately investigate all cooperation and communication involving the NBA.”

Also on Tuesday, several popular Chinese acting and singing stars said they would boycott the exhibition games — putting the Los Angeles Lakers against the Brooklyn Nets.

An associated hashtag, “Several stars quit NBA games”, was the most-discussed on China’s leading social media platform Weibo on Tuesday morning, with more than 350 million “reads”.

Nets players, executives and NBA China officials were to appear at a publicity event at a Shanghai primary school on Tuesday afternoon, but the league abruptly cancelled it just two hours before it was to start, giving no explanation.

NBA representatives did not immediately respond to AFP queries about the cancellation or whether the games themselves — set for Thursday in Shanghai and Saturday in the southern city of Shenzhen near Hong Kong — would go ahead.