Beijing strongly opposes trade restrictions included in the new US defense law.

The National Defense Authorization Act (NDAA), signed last week, prohibits the use of federal funds to buy railroad cars and buses from China and slows the lifting of sanctions on technology giant Huawei, Voice of America reported.

"We have noted that the U.S. defense authorization act... contains a number of adverse provisions against Chinese enterprises, which China firmly opposes," Chinese commerce ministry spokesman Gao Feng said at a regular briefing.

This law is expected to affect the activities of two Chinese companies: CRRC Corp., a railcar manufacturer. and BYD Motors, which sells electric buses in the US.

The new restrictions contained in the bill do not allow Washington to remove Huawei from the US Commerce Department blacklist, which prohibits US firms from working with the company.

"China will pay close attention to the impact on Chinese enterprises during the implementation of the bill, and take all necessary measures to protect the legitimate rights and interests of Chinese enterprises," Gao said, without offering details of the possible countermeasures.