China has exempted some U.S. imports from its 125% tariffs and is asking firms to identify critical goods they need levy-free, according to businesses notified, in the clearest sign yet of Beijing's concerns about the trade war's economic fallout.

An American business group said that Chinese officials had been surveying companies about American products that are crucial to their supply chains.

China has quietly exempted from tariffs some semiconductors made in the United States, in an attempt to protect its leading technology companies from a bitter trade showdown with President Donald Trump.