Strikes costing Qld miner billions: union

The cost of ongoing strikes at BHP Billiton Mitsubishi Alliance (BMA) mines in central Queensland is about to hit the $2 billion mark, a union says.

Thousands of workers at seven BMA mines have been involved in rolling stoppages since June last year.

Last week, the workers ramped up their action from 24-hour stoppages to week-long stoppages amid protracted negotiations over a new enterprise bargaining agreement.

Construction Forestry Mining and Energy Union (CFMEU) district president Stephen Smyth says the months of industrial action have so far cost BMA an estimated $2 billion.

Mr Smyth said the mining giant was now bypassing the union and planned to hold a vote on the agreement directly with workers by the end of the month.

"Members don't support the agreement," Mr Smyth said.

"We will be looking at escalating our strike action."

He says the company has reneged on an in-principle agreement with the union regarding rosters.

The agreement prevented the company from imposing longer hours and more odd-hour shifts on workers without their approval.

BMA has been contacted for comment.