A proposed new round of tariffs on some 300 billion US dollars in goods from China, if effectively implemented, would stifle the US economy, a business advocacy group has said.

"Rather than creating more opportunities for US business, sweeping tariffs will restrict US agriculture, goods, and services exports and raise costs for businesses and consumers," the United States Council for International Business (USCIB) said in written comments recently submitted to the Office of the US Trade Representative (USTR).

The warning came as the USTR is holding a series of hearings to solicit public responses to the proposed tariff hikes, the fourth round since Washington started trade tensions with Beijing by raising tariffs on Chinese imports last year.

USCIB's China lead Eva Hampl testified before a panel of government trade officials on Friday, warning that the proposed list "includes categories of products that only impact US companies, and not their global competitors."

"Ceding market share to competitors is not weakening the Chinese economy. It is merely weakening the US market," Hampl said.

Dozens of other witnesses, representing such industries as tea, information technology and retail, also attended Friday's hearing, during which most of them explained how the additional tariffs would harm businesses, disrupt supply chains, and add costs to consumers.

Two more days of hearings are scheduled for next week.