Chinese firms have managed to gain access to U.S. strategic dual-use technologies via certain third parties, he said, referring to loopholes that have allowed Chinese companies access to U.S. technologies despite restrictions.

"U.S. officials will continue to step up tracking and tracing operations aimed at the smuggling of advanced semiconductors made by Nvidia and Advanced Micro Devices," he said.

The expanded export restrictions come at a time when tensions between Washington and Beijing have been rising with the Trump administration ratcheting up tariffs against China.