A strike contagion is apparently spreading in Australia's labor sector. Days after thousands of public workers in New South Wales walked off their job over a state pay cap, coal miners of BHP Billiton resumed their job walk off on Saturday over pay and work condition disputes with management.

The industrial action at three BHP Billiton Mitsubishi Alliance (BMA) Mines is expected to continue until Sunday and may spread to BMA's four other mines depending on the result of a member vote later this week, Construction, Forestry, Mining and Energy Union Division President Stephen Smyth said.

There are about 3,500 coal miners who have been on rolling work stoppages since June, which is the first strike to hit BHP's Australian coal mines in 10 years. BHP previously offered the workers $15,000 per head flat bonus as part of a new enterprise deal, but the coal miners are wary of signing a proposed deal which would give BHP the right to determine the start and finish times for shifts and reallocate shifts on just 28-day notice.

The rolling strikes had several six-hour work stoppages while unions continued negotiations with BHP and Mitsubishi Development over the new enterprise agreement. Smyth said in June that the work stoppages were for talking to union members en masse.

However, the work stoppages excluded union miners at the Broadmeadow colliery who held separate agreements with BMA.

BMA then said that the alliance did not intend to replace the miners with contractors, but urged them to reconsider their work stoppage plans.

BHP and Mitsubishi own equally BMA, which has about 4,800 workers. The mine has a yearly production capacity of 58 million metric tons, exported overseas to steel manufacturers. Analysts estimated that a full-day strike would cut the mine's output by 130,000 metric tones and prolonged strikes could keep coal prices at current price levels.

Coal used for steelmaking went up 47 per cent to a record high of $330 per metric tonne for three-month contracts that began April 1. However, in June, Asian steel producers agreed to pay Anglo American a lower $315 per tonne for the September quarter.

BHP Chief Executive Office Marius Kloppers said in August that the job walk offs only had a modest impact on coal production.

"BHP believes it's negotiated enough and further talks won't assist," Mr Smyth told Bloomberg.

"Negotiations should be alive and active. BHP is setting itself up to roll out an agreement that it will present to workers that the union doesn't support in any shape of form," Mr Smyth added.