"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."

The US basketball league is facing a mounting backlash in China over a tweet last week by Houston Rockets' general manager Daryl Morey expressing support for protesters in semi-autonomous Hong Kong who have staged increasingly violent demonstrations to demand more freedoms.

The announcement made clear CCTV was referring to two annual NBA exhibition games in China, which this year pit the Los Angeles Lakers against the Brooklyn Nets.

They are set to play in Shanghai on Thursday and in the southern Chinese city of Shenzhen on Saturday.

CCTV made no mention of games in the upcoming regular season, nor did it give any further details on its plans to review all ties with the NBA.
The move by CCTV is the latest indication that the NBA may suffer significant damage in the hugely important Chinese market.

CCTV and Tencent Holdings -- which streams NBA games in China -- had already said they would halt plans to broadcast Rockets games, while major Chinese sponsors have also cut ties.

Nets players, executives and NBA 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 whether the Lakers-Nets contests would be cancelled.

The NBA has called Morey's tweet "regrettable" but commissioner Adam Silver on Monday insisted that the league supported his right to express his opinions.

"We are strongly dissatisfied with and oppose (Silver's) comments in support of Morey's right to free expression," CCTV's statement said.