Commodity trading company Trafigura has taken effective control of Nyrstar operations in a debt-restructuring deal, raising concerns over a $291 million loan, guaranteed by the state government, to upgrade the Port Pirie smelting plant.

Mr Lucas said he had been formally briefed on the planned capital restructure by Trafigura's chairman Jeremy Weir, who re-affirmed the importance of the Port Pirie site to his company's global operations.

"In my conversation with Mr Weir, I sought and received his commitment to ongoing constructive talks regarding the repayment of our taxpayer-guaranteed loan," Mr Lucas said.

"He recognised and re-affirmed the importance of Port Pirie to the company's global operations and understood the government's clear objective to protect jobs at the smelter."

The treasurer said Nyrstar and the government would continue to hold discussions in relation to the guaranteed funding arrangements, targeting a mutually-binding agreement as soon as possible.

"We remain hopeful of a successful resolution, not only for taxpayers, but for the people of Port Pirie, the smelter's employees and their families," he said.

Australian Associated Press