The Construction, Forestry, Mining and Energy Union (CFMEU) says it will take resources giant Rio Tinto to court if it cannot resolve a dispute over redundancy packages at a central Queensland mine.
About 30 CFMEU members at Rio Tinto's Blair Athol coal mine, near Clermont in central Queensland, have begun a series of rolling stoppages that will end tomorrow.
The company is closing the mine next Friday but the CFMEU is accusing the mine operator of discrimination.
The CFMEU says non-union members, who are on individual agreements, have been offered larger redundancy payouts.
CFMEU spokesman Glenn Power says if the matter is not resolved it will take legal action.
"That's in the hands of our legal department and they're quietly confident," he said.
He says members are prepared for a lengthy court battle.
"They're fully aware of what's involved - we've backed them before and we'll back them again," he said.
"This fight isn't going to finish on the ground, this fight's going to continue on in the courts.
"We'll fight Rio if it takes five, six, seven years to get justice." Rio Tinto will not comment on the legal threat but it reissued a statement from last month, saying its union agreement is fair.