CHINA's top chipmaker, Semiconductor Manufacturing International Corp (SMIC), "warrants investigation" as the company appears to have violated US sanctions by supplying components to Huawei Technologies Co, a US lawmaker said.

"It sure looks like it did" violate sanctions, said Texas Republican Congressman Michael McCaul. SMIC continues "to try to get our intellectual property."

Huawei uses an advanced 7-nanometer processor built by SMIC to power its latest smartphone, indicating that China is making headway in its push to produce cutting-edge semiconductors despite US sanctions.

Existing rules require any company that intends to supply Huawei with US technology, which is present throughout SMIC's operations, to get approval from Washington. It's unclear whether SMIC has a US license to supply Huawei.

Mr McCaul, chairman of the House Foreign Affairs Committee, has been vocal in protesting what he considers insufficient enforcement of the Entity List, which is enforced by the Commerce Department's Bureau of Industry and Security.