A worker sprays corrosion inhibitor on a furnace at a steel mill of Dalian Special Steel in Dalian, Liaoning province, China September 26, 2018. REUTERS/Stringer

SHANGHAI (Reuters) - China has filed a request with the World Trade Organisation to establish an expert group to determine the legality of tariffs imposed by the United States on imports of steel and aluminum, the Ministry of Commerce said late on Thursday.

In a statement posted on its website, the ministry said the U.S. decision to adjust tariffs on imported steel and aluminum in March this year was an act of protectionism that seriously undermined multinational trade rules.

It said consultations with the United States under the WTO dispute settlement mechanism had failed to resolve China’s concerns, prompting it to ask for the expert group to be established.