The Construction Forestry Mining Energy Union said while a high vaccination rate of the general populous was necessary to stop outbreaks it did not  support mandatory vaccines across the mining and oil and gas sectors.

In a statement the CFMEU said it was not practical to impose compulsory vaccination across mine sites.

It said mine site workers were not on the front line fighting COVID-19 outbreaks and should be allowed to make a personal decision on whether to get vaccinated.

The union's opposition follows speculation the mining industry could require workers to be fully vaccinated before boarding a flight to site.

Western Australia has a hard border with Victoria and New South Wales following an outbreak of the Delta variant of COVID-19.

This border requires anyone entering WA from COVID-19 hotspots such as NSW, with legitimate causes, to have had at least one vaccine shot.

Fortescue Metals Group and Mineral Resources are strongly encouraging their fly-in, fly-out workforce to get vaccinated but have stopped short of making vaccination mandatory.

The CFMEU said it was not up to industry or employers to make vaccines mandatory.

"Decisions about mandatory vaccination for any group of workers are made by health authorities and not by individual employers or employer associations," it said.

The union said its members had been subjected to "mixed messages and misinformation" about vaccines and were concerned about their "legal rights".

It has become widely accepted by health professionals and authorities that Australia cannot open its international borders and allow free travel without 80% of the population vaccinated.

However, it is believed that without mandatory vaccination it will be hard to reach this level of vaccination.

According to Melbourne University research, despite the severity of the NSW and Victorian outbreaks, vaccine hesitancy in the population is about 22%.