Thousands of coalminers on strike at BHP's Queensland operations

Sydney Morning Herald reports that between 3500 and 4000 miners have walked off the job at BHP Billiton's coal operations in Queensland.

Production will be affected at at least six mines operated throught the BMA joint venture between BHP Billiton and Mitsubishi Corporation. They include Blackwater and Goonyella, Gregory Crinum, Peak Downs, Saraji and Norwich Park.

The strike is expected to last for a week and BHP will try to continue some production using staff or contract labour.

The main stumbling block between the CFMEU mine workers union and BHP is not wages, but proposed changes to work practices, along with a range of other issues including housing and union representation. The industrial action affects mining, manufacturing and electrical unions.

The Australian reports the strike has the potential to go for three months, with the union's president, Stephen Smyth, saying the membership was prepared to be out that long to pressure the company into an acceptable agreement.

The union is fighting BHP's refusal to provide fatigue crib breaks for employees working 12-hour shifts on consecutive nights, as well as clauses that would permit managers to permanently replace employees in safety roles.

The dispute at the BMA joint venture has been ongoing since late 2010. Workers are also striking at Port Kembla's coal loader, where the loader was shut down the first week of February and with a 48-hour strike called earlier this week, Sydney Morning Herald said.

ABC News says the strike would be the biggest since the prime ministership of John Howard, whose 11-year term ended in 2007.

BHP's Mitsubishi Alliance (BMA) is Australia's largest supplier of coking coal and provides 20% of global production.