Alan Estevez, undersecretary of commerce for industry and security, announced the decision at an industry gathering last week. The exemptions, initially granted for one year in October last year, were provided to several companies, including South Korea's Samsung Electronics and Taiwan Semiconductor Manufacturing, who have invested billions in building plants in China.

The decision to extend the exemptions reflects the challenges faced by US authorities in isolating China from high-tech goods in a highly integrated global industry.

The US has been trying to keep advanced chips out of Chinese hands by limiting exports not only from American manufacturers but also those made by allies. However, US and foreign chip makers have resisted these efforts, and governments in Asia and Europe have also pushed back.

The most vocal criticism has come from South Korea, whose largest export market is China.