A U.S. congressional commission on Tuesday called on American basketball stars to end endorsements of Chinese sportswear firms that use cotton grown in China's Xinjiang region, warning against complicity in forced labor they say takes place there.

In a letter to the National Basketball Players Association, the chairs of the bipartisan Congressional-Executive Commission on China said more than a dozen NBA players had deals with the China-based ANTA, Li-Ning and Peak sportswear firms prior to the publication of recent Western media articles saying the companies had backed continued use of Xinjiang cotton.

"Players have continued to sign new deals with Anta Sports," the letter from Senator Jeff Merkley and Representative Jim McGovern added.