"The US government's wanton launch of sanctions against Chinese companies without real evidence is not a wise choice," foreign ministry spokesman Kong Quan told a regular briefing.

A State Department notice published in the latest issue of the Federal Register said the companies are being penalized for transferring to Iran "equipment and technology controlled under multilateral export control lists."

A company from Taiwan and one from North Korea have also been targeted by the US decision.

"We have formulated a series of regulations and laws to prevent the spread of weapons of mass destruction," Kong said. "We will crack down on such actions."

The seven Chinese companies include China North Industry Corporation (Norinco) and China Great Wall Industry, which both have close ties to the People's Liberation Army.

The two are already under US sanctions for violating various export control regimes, and it was not immediately clear how the new measures will affect their business.