The Australian Workers' Union has flagged a possible legal challenge to BHP's decision to lock out workers who refuse to be vaccinated for COVID-19.
The mining giant on Thursday said it would not let unvaccinated staff, contractors and visitors onto any of its Australian work sites from early next year.
"We have undertaken a thorough assessment and believe that this is the right path forward to protect the health of our people, their families and the communities where we operate," BHP Minerals Australia president Edgar Basto said.
The announcement drew immediate fire from the mining union, the CFMEU, a stance backed by the AWU on Friday.
"We are engaging with our members to discuss this announcement and we will be considering all options, including legal avenues," AWU Queensland secretary Steve Baker said in a statement.
The union accused BHP of making a significant workplace change without bothering to talk to its workforce or their representatives.
"Because of this tin-eared, top down approach, BHP risk alienating large sections of the workforce who might otherwise be supportive of vaccinations," he said.
AWU national secretary Daniel Walton said education, easy access to jabs and incentives were the way forward, not vaccine mandates.
Queensland Health Minister Yvette D'Ath said jab mandates in individual workplaces were matters for business owners.
But she said there should be a conversation at the national level about any sector-wide mandates.
Ms D'Ath said all workplaces should be consulting with their workforces if they decide to require vaccinations.
"We want to work with the unions on this, and I'm sure BHP understand the importance of doing that as well," she said. "But this is a decision for BHP."
The mining company has said COVID-19 jabs will be a condition of entry for all its work sites, including mines and office spaces, from no later than January 31 next year. Some sites will impose the rule earlier than that.
Mr Basto has promised to work closely with BHP's workforce as it moves towards the full implementation of its vaccine policy.