Micron Technology Inc shares are around 5.4% lower in pre-market deals after China ruled its products posed “serious network security risks”.
The Cyberspace Administration of China (CAC) on Sunday announced the company, which is the biggest US maker of memory chips, “posed significant security risks to China’s critical information infrastructure supply chain”.
As a result, it ordered “critical national infrastructure operators” to stop purchasing products from Idaho-based Micron.
The move follows a seven-week investigation into Micron by the CAC, a probe widely seen as retaliation for US efforts to curb China’s access to critical technology.
Last October, Washington introduced expansive chip export controls.
The US commerce department said it strongly opposed the action which it said had “no basis in fact”.
“This action, along with recent raids and targeting of other American firms, is inconsistent with the PRC’s assertions that it is opening its markets and is committed to a transparent regulatory framework,” the commerce department said.