SK hynix Inc. said Thursday it began an internal investigation into how its memory chips ended up in a new smartphone made by Huawei Technologies Co.

Bloomberg News previously reported that the South Korean chipmaker's DRAM -- LPDDR5 -- and NAND Flash memory are used in the Chinese tech company's latest smartphone Mate 60 Pro.

SK hynix's memory products were "an isolated example of materials" the Chinese handset maker sourced from overseas, according to the report.

"SK hynix no longer does business with Huawei since the introduction of the U.S. restrictions against the company and with regard to the issue, we started an investigation to find out more details," the chipmaker said.

"Also, SK hynix is strictly abiding by the U.S. government's export restrictions," it added.

SK hynix stopped supplying chips to Huawei in the fall of 2020, after Washington banned the supply of semiconductors made with U.S. equipment, software and design to the Chinese company without prior approval, citing security concerns.

At that time, SK hynix was known to depend on Huawei for some 10 percent of its sales.

SK hynix said it reported to the Bureau of Industry and Security under the U.S. Commerce Department, which deals with issues involving national security and high technology, before beginning the investigation.