The Single Bargaining Unit – made up of the Construction Forestry Mining and Energy Union, the Australian Manufacturing Workers Union and the Communications, Electrical and Plumbing Union – said while progress had been made in recent negotiations, there were still outstanding conditions that had not been agreed upon, which had prolonged the negotiations into next month.

“After two more days of negotiations the issues listed by the SBU … are still not agreed,” the SBU said in its latest update to members.

“Some progress was made and various clauses agreed in principle but the SBU does not agree that the list in the company’s latest flyer are agreed – in fact, it is quite misleading.”

The main outstanding issues are preference for current employees over external applicants for jobs; special payments for some employees only; loss of Christmas Day and Boxing Day as non-working days across the sites; and no reinstatement of union representation rights removed by Work Choices.

The SBU said BMA had agreed to meet again on Saturday September 10.

A spokesperson for BHP Billiton told ILN BMA was continuing to meet and negotiate with the unions and believed good progress was being made.

"Both parties have acknowledged BMA’s intention to have negotiations completed so as to allow employees to vote on a proposed agreement in early September,” the spokesperson said.

"This is consistent with feedback that we are getting from employees who are expressing frustration about the time negotiations are taking and about the impacts of ongoing industrial action.

"BMA is continuing to do all it can to avoid further disruption and to ensure negotiations are completed as quickly as possible."

In a press conference last week BHP Billiton chief executive Marius Kloppers criticised the productivity of its Australian workforce and the rising unit cost of labour to produce coal.

He said BHP Billiton was suffering a “lag” effect of the commodity boom, which had lead to costs for labour and contractors contributing to $US878 million extra in costs in the last financial year.

“For us, there are two aspects that we always emphasise when we talk about total labour productivity, or total cost per unit,” Kloppers said.

“One is what does it cost for a unit of labour [and] the second item is, what are you able to produce out of the unit of labour?

“So what we have seen, particularly on the capital side in Australia, is that we have had negative impacts, or the industry has had negative impacts, on both those elements.

“So labour has become more expensive and unbalanced. It has become less efficient.”