(Reuters) -Trafigura unit Nyrstar said on Thursday it had started casting antimony metal in a pilot plant at its Port Pirie metals facility in South Australia, a project listed as part of the U.S.-Australia Critical Minerals and Rare Earths Framework.

The milestone follows an A$135 million ($87 million) investment from the South Australian and Australian governments in August as part of the country's strategy to become a key supplier of critical minerals to Western allies.

Antimony, an alloy hardener for other metals, is critical to the manufacture of semiconductors used in electronics and defense applications.

Initial batches of antimony metal are expected to be exported in the first half of next year, with the target of ramping up production to 2,000 tons per annum by end of 2026, the company said in a statement.

The facility could scale up to 5,000 tons of refined antimony metal per annum by 2028, the company said.

Australia signed an agreement with Washington in October aimed at countering China's dominance in critical minerals needed for industries spanning artificial intelligence to defence systems.

"Nyrstar's aim is to explore possible production of not just antimony, but bismuth, tellurium, germanium and indium - minerals critical to the clean energy future and important defence and technology sectors," Premier of South Australia Peter Malinauskas said in a separate statement.

On Wednesday, Australia's trade minister said the country is seeing more interest in its strategic critical minerals reserve from allies including the European Union since it signed a deal with the United States in October.