BHP Billiton declared force majeure at its Bowen Basin coal mines in Queensland, Australia.
Ongoing labour woes and heavy rains forced the world's biggest miner to make the announcement. The move could push coal prices higher, since the Bowen Basin supplies about one-fifth of the world's metallurgical coal.
"Now that this very important supply block is dropping out of the market, it's got the potential of driving prices up… I'd say within the next few days we'll see life (in prices)," said UBS analyst Tom Price to Reuters.
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 jointly-owned coal basin is run by Mitsubishi Development Pty Ltd and BHP Billtion, the BHP Billiton Mitsubishi Alliance (BMA). 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.