The US has launched a new trade enforcement action against China at the World Trade Organization (WTO) over the export duties it continues to levy on key raw materials.

Announced last week, the trade enforcement case concerns the duties of between five and 20 per cent that China charges on antimony, cobalt, copper, graphite, lead, magnesia, talc, tantalum and tin, which the US is protesting on the basis that they offer an unfair competitive advantage to China at the expense of businesses elsewhere in the world.

It marked the 13th trade enforcement case launched against China at the WTO during Barack Obama's presidency, more than any other WTO country over the same period. It was also noted that the US has won every case that has been decided so far.

Additionally, since this announcement was made the US has expanded its challenge further to also encompass China's export duties on chromium, as well as the quotas it imposes on antimony, indium, magnesia, talc and tin.

The US argues that this unfair policy makes it easier for Chinese manufacturers to produce lower-priced goods, creating an uneven playing field and creating pressures on non-Chinese producers to shift production operations, technologies and jobs to China.

It was also noted that China agreed to eliminate export duties on these products upon joining the WTO, but has so far failed to follow through on the commitment.

US trade representative Michael Froman said: "Today's action again makes clear that we will not hesitate to challenge export policies that harm US manufacturers by restricting their access for key inputs into products made here in America.

"The restraints we challenged last week, along with the ones we have included today, are part and parcel of the same troubling policy - one that provides advantages for China in important manufacturing sectors at the expense of the rest of the world."