BHP's Australia coal miners returning to picket line

Workers at Australia's Bowen Basin coal mines, owned jointly by BHP Billiton and Mitsubishi, have once again given strike notice.

Reuters reported the union will strike for seven days starting next week, after workers rejected a new employment contract proposed for the second time.

A strike earlier this year in the Bowen Basin forced BHP to declare force majeure on shipments from the mines, thus releasing the company from legal obligations emanating from supply disruptions. The strike, along with heavy rains, was also blamed for an 8% drop in production of coking coal last quarter.

BHP Billiton and its workers have been bargaining for over a year but have been unable to resolve their differences. BHP Billiton has taken offers directly to the workers, but the offers were voted down. The key sticking point is work schedules.

Reuters reported a BHP spokeswoman saying further industrial action was "unnecessary and would be harmful for all concerned".

A spokesman for the union said the company is "radically out of touch with its workforce, an overwhelming majority of whom is still not prepared to give up crucial conditions around safety, rosters, housing and equality for contractors."

The threatened work stoppage could not come at a worse time for the world's biggest miner, having announced earlier this week that it is scaling back its most ambitious programs and will not spend the $80 billion previously set aside for expansion by 2015.

BHP's stock price has also taking a beating, falling to its lowest level in three years on the Australian stock exchange Wednesday.

The jointly-owned coal basin is run by the BHP Billiton Mitsubishi Alliance (BMA), a combination off Mitsubishi Development Pty Ltd and BHP Billiton. The group is Australia’s largest coal miner and exporter.

The Bowen Basin contains Australia's largest coal reserves and one of the world's largest deposits of bituminous coal. Annual capacity of around 58 million tonnes a year represents about 20% of annual globe trade in metallurgical coal.