China voiced firm opposition to the US decision to impose unilateral sanctions on two Chinese companies, the Ministry of Commerce said on Saturday, urging Washington to "promptly correct its wrongdoings".

On Thursday, the US State Department announced Cuba-related sanctions on China National Electronics Import & Export Corporation, an electronics and engineering company, and Beijing H&C Technologies Co Ltd, a security equipment supplier.

In a fact sheet, the department said the measures targeted "China-based suppliers of the regime's military forces" and alleged that the two companies had supplied components and equipment to Cuba's military through a Cuban procurement firm.

Imposing unilateral sanctions on Chinese companies on grounds involving a third party "violates international law and the basic norms governing international relations", a ministry spokesperson said in a statement.

The spokesperson added that Washington has recently stepped up sanctions and pressure on China, introducing a series of discriminatory restrictions in quick succession.

Such measures have seriously harmed the rights and interests of Chinese companies, the spokesperson said, adding that they run counter to the important consensus reached by the two heads of state and undermine the stability of bilateral economic and trade relations.

"China urges the United States to promptly correct its wrongful practices and reserves the right to take necessary measures to safeguard its legitimate rights and interests," the spokesperson said.