The company’s own investigation team and inspectors from SafeWork SA began assembling at the mine late last week.

Rumours of stand-downs and lay offs in the underground crews have been circulating through Roxby Downs since the main ore-haul shaft was blocked due to a mechanical failure about 10.30pm on Tuesday last week.

Union officials have claimed a cable broke in the fully-automated system that take ore to the surface at the copper, gold and uranium mine.

However, BHP Billiton will say only that the system suffered a mechanical “breakdown” in one of two ore haulage systems.

“Olympic Dam’s mine planning team is currently examining what impact the temporary closure of the Clark Shaft will have on mine production, planning schedules and budget,” BHP Billiton said in a prepared statement last week.

“This work is expected to be completed in the course of the next two weeks and will run in parallel with both the government and company investigations into the incident,” it said.

Enquiries this week to BHP Billiton head office in Melbourne have brought no further update.

“We are continuing to work in the same way we always do in terms of allocating work where it's required. If we have any further update we'll let you know,” BHP Billiton’s media relations spokesperson, Samantha Evans, said Tuesday when queried about whether there had been staff or contractor stand-downs because of the mishap.

Ms Evans said she was unaware of any stand-downs.

Martin O'Malley from the Construction Forestry Mining and Energy Union said he has been given little information from BHP Billiton, but union members were keeping him informed.

"They said they felt it was most likely a break in the cable … from what they tell me (the load of ore) could be from anywhere from the ground down to 800 metres," Mr O’Malley said.

He said the union believed the designer and builder of the haulage system was being brought in to help in the investigation into what went wrong.

The mine is continuing to operate, using a secondary shaft and haulage system to bring ore to the surface.

However, it is understood the secondary system in the Whenan Shaft does not have the same capacity as Clark Shaft.

No one was injured in the Clark Shaft mechanical failure.

BHP Billiton has said “safety of our workforce will take priority in deter­mining any re-start of haulage operations (in Clark Shaft).”