China’s cyberspace regulator has instructed companies including Alibaba to halt orders for Nvidia’s RTX Pro 6000D, a semiconductor for workstations that can be repurposed for artificial-intelligence applications.

The Cyberspace Administration of China told companies this week to stop testing the chip and cancel existing orders, according to people familiar with the matter, who asked not to be identified because the decision isn’t public. Several companies had indicated before the directive that they would buy tens of thousands of the semiconductors, which Nvidia designed to avoid triggering U.S. restrictions on sales of advanced AI chips to China, according to an earlier report in the Financial Times.

Nvidia shares slid 2.7% in U.S. trading, while the stock of rival Advanced Micro Devices fell nearly 1%.