WASHINGTON, United States (AFP) — The United States said yesterday it was imposing steep import duties on Chinese imports of alloy aluminium sheet valued at nearly US$1 billion, which Washington says have been dumped on the US market.

Trade relations between the world’s two top economies on Tuesday were at the brink of all-out conflict, with US President Donald Trump having threatened late Monday to place tariffs on almost all of Chinese exports to the United States.

Tuesday’s announcement was part of a process begun in November that marked the first time in 33 years that the US Commerce Department had self-initiated the process of imposing anti-dumping import duties by itself — not at the behest of US manufacturers.

“The Department of Commerce will do everything in its power to stop the flow of unfairly subsidised or dumped goods into US markets,” US Commerce Secretary Wilbur Ross said in a statement.

The department said yesterday it had reached a preliminary conclusion that Chinese exporters had sold the aluminium sheet in the US at 167.2 per cent below fair value.

As a result, US Customs and Border Protection will begin collecting cash deposits from importers based on the alleged dumping rates.

A similar Commerce Department process found in February that the imports were subject to impermissible Chinese subsidies.

US imports of Chinese-made common alloy aluminium sheet in 2017 were valued at about US$900 million, according to the Commerce Department, up about 50 per cent from 2016.

A final determination is due in late 2018 and could be blocked by the independent US International Trade Commission, which has disagreed with several of the Trump Administration’s dumping- and subsidy-related tariff decisions.

China is also subject to 10 per cent US duties on primary aluminium imports announced in March, but the United States imports only a marginal amount of that substance from China every year.