Asbestos has been found in equipment sourced from China for Port Pirie's Nyrstar $563-million smelter redevelopment.

SafeWork SA is investigating breaches of work health and safety laws and how the importation was allowed to occur.

The watchdog found the friable asbestos fibres in contaminated plant equipment imported by China over the past year.

Imports of asbestos have been banned in Australia for more than a decade.

Australian Workers Union (AWU) state secretary Peter Lamps said the eight contaminated heat exchanger tubes, which were each about the size of a bus, were meant to dissipate heat from the production process.

He said workers discovered the asbestos, and protective equipment looked to have minimised any exposure.

"We understand it was the keen eye of workers that identified the material," he said.

"I think it was more by good luck given the fact that in a lead smelter site there are very high levels of PPE and respirators worn ... this may well have provided a degree of safety or security for those workers."

Mr Lamps said there needed to be a high-level inquiry into why asbestos-tainted products were escaping detection at the border.

"These pieces of equipment aren't exactly able to be shipped in a shipping container or in a small box. These heat exchangers are at least 10-metres long," he said.

"We really need to understand how and why a contractor is able to land this contaminated product into the state or into the country and it's always workers that seem to identify the contamination."

Nyrstar said all work in the area where the asbestos was found was stopped immediately and was barricaded off.

"Areas containing asbestos have also been sprayed with a soluble adhesive and wrapped with a plastic sheeting to prevent any spreading of the material," it said in a statement.

"Nyrstar is incredibly disappointed to find that the new acid plant vessels contain asbestos.

"Nyrstar's contract with the supplier of the acid plant explicitly prohibited the use of asbestos in the equipment. Nyrstar is investigating the circumstances which led to asbestos being used."

SA Government demands talks about Border Force's failures

It has been revealed Nyrstar informed SafeWork SA about the asbestos which was found in the plaster coating the heat exchanger tubes on August 12 and that South Australia's Industrial Relations Minister John Rau was advised yesterday.

The company employed specialists to "contain the exposed asbestos" on August 14.

Mr Rau said the State Government had called for urgent talks with the Federal Government after repeatedly raising Australian Border Force's failures to detect asbestos-tainted imports.

He said SafeWork SA had prohibited all work in the vicinity of the asbestos which was in the acid plant section of the project.

"The discovery of asbestos in imported plant is appalling," he said.

"It is disgraceful that more than 10 years after a total ban on asbestos was imposed across the nation, Commonwealth border guards are still failing to keep these products out of this country."

South Australian senator Nick Xenophon said he wanted an audit of all imported products which could potentially contain asbestos.

"In the five years it seems that someone has been dropping the ball in relation to this and there needs to be a thorough audit of all those building products that have come into this country that could potentially contain asbestos," Senator Xenophon said.

He said a Senate inquiry that was looking into asbestos should be re-convened.

"Border Force also needs to also stop the boats full of asbestos because that is what is happening now," he said.

A spokeswoman for Immigration Minister Peter Dutton said he would not make a comment on the situation.

The redevelopment project was to cut lead emission and convert the smelter into a mixed metals processing plant.

The project was expected to be operational by the second half of 2017.

Asbestos-tainted products sourced from China were recently found to have been used on the new Perth Children's Hospital and a Brisbane high-rise building.