As of midday yesterday, over 1200 PCR tests and 850 rapid antigen tests had been completed across Fortescue's operational sites.
All rapid antigen tests have returned negative results and results are pending for the PCR tests, which are processed in Perth.
It comes after a maintenance contractor who had been at FMG's Cloudbreak site from July 20-27 returned a weak positive test for COVID-19 on Wednesday.
He has subsequently returned a negative test result.
There have been no further positive cases in Western Australia, despite the man visiting a number of pubs over the weekend.
FMG suspended certain operations while the COVID-19 testing was conducted, with full operations expected to resume by last night.
The incident is not expected to have any impact on FMG's iron ore shipments.
"The safety of all our team members, their families and our local communities is our highest priority," FMG CEO Elizabeth Gaines said.
"We have robust COVID-19 management protocols in place and are taking every precaution to ensure COVID-19 does not impact our operations.
"Our incident management team has worked effectively to assist with contact tracing efforts and our decision to invest in rapid antigen testing has allowed us to immediately test our team members."
Gaines encouraged all FMG workers to get vaccinated.