The House of Representatives security panels, scrutinising ZPMC’s installation of Swiss engineering group ABB’s equipment onto US-bound ship-to-shore cranes, in January invited ABB executives to public hearings to clarify its relationship with ZPMC, which they said raised “significant concerns”.

“ZPMC takes the US concerns seriously and believes that these reports can easily mislead the public without sufficient factual review,” it said in a filing, referring to the probe by the homeland security and strategic competition committees.

“The cranes provided by ZPMC do not pose a cyber security risk to any ports,” it said.

ABB has said it sold its control and electrification equipment to many crane manufacturers, including Chinese companies, which in turn sold cranes directly to US ports.

The US and China, the world’s biggest economies, frequently accuse each other of cyber attacks and industrial espionage.

Washington this year said it had disrupted a Chinese cyber spying operation targeting US infrastructure and was investigating Chinese vehicle imports for national security risks.

It previously barred Chinese telecom companies.

ZPMC said the cranes it supplies are used in ports around the world, including the US, and comply with international standards and applicable laws and regulations.

Listed on the Shanghai stock exchange, ZPMC is one of the largest port machinery manufacturers in the world, owning a fleet of more than 20 transportation vessels, according to its website.

ABB generates 16% of its sales from China, second only to the US market at 24%.