The Trump administration launched a new trade case against China on Tuesday, opening the first U.S. government-initiated anti-subsidy and anti-dumping probes in decades into imports of Chinese aluminum alloy sheet.

The seldom-used tactic is aimed at accelerating the imposition of duties against unfairly subsidized and dumped products. U.S. companies and industries claiming injury from imports would normally first ask the Commerce Department to open such probes, but government-initiated cases skip that step.

"President (Donald) Trump made it clear from day one that unfair trade practices will not be tolerated under this administration, and today we take one more step in fulfilling that promise," Commerce Secretary Wilbur Ross said in a statement.

The case shows "that we stand in constant vigilance in support of free, fair and reciprocal trade," he added.

The Commerce Department last initiated an anti-subsidy duty investigation in 1991 on softwood lumber from Canada and last initiated an anti-dumping probe in 1985 on semiconductors from Japan.

Ross told U.S. aluminum industry executives on a conference call that Commerce has evidence that China's aluminum producers were selling flat-rolled sheet products in the United States at prices below fair value and were benefiting from unfair government subsidies.

"Available evidence also indicates that U.S. producers of aluminum sheet are suffering injury caused by these imports," Ross said.

The Commerce Department estimated anti-dumping duties of about 56.54 percent to 59.72 percent in the aluminum case. It said imports from China of the flat-rolled metal typically used in construction and in transportation and electrical equipment totaled about $603.6 million in 2016.