Tugboat workers at Australia's biggest iron ore port have approved a plan to go on strike, which would halt a quarter of the world's iron ore exports, if they are unable to resolve a dispute over leave and pay, their union said on Monday.
Deckhands in the Maritime Union of Australia (MUA) voted to strike for one, two or seven days, but remain in talks with tugboat operator Teekay Shipping Australia to resolve the dispute, the union said.
No date or timeframe has been set for a strike, which would halt iron ore shipments by BHP Billiton and Fortescue Metals Group. Together they supply more than half of Australia's iron ore exports.
"Industrial action is always a last resort and we still hope that we can come to an agreement without having to take the action which has been sanctioned by the Fair Work Commission," MUA Assistant Western Australia secretary Will Tracey said in a statement.
If the workers decide to go on strike, they must do so within 30 days, and must give Teekay three days' notice ahead of any strike.
Iron ore is Australia's biggest export earner, with the value of exports forecast to surge 35 percent to A$76.8 billion ($71.8 billion) in the year to June 2014 from a year earlier, according to the Bureau of Resources and Energy Economics.
"Given the current wages and conditions, we think it would be irresponsible for the MUA to take industrial action that would put a stop to one of Australia's most critical national exports," a BHP Billiton spokeswoman said.
BHP, which holds the licence for the tugboats at Port Hedland, estimated a strike would cost suppliers who use the port around A$100 million ($93.5 million )a day.
BHP said it remained hopeful that Teekay would be able to reach an agreement with the maritime unions.
Teekay declined to comment on its negotiations with the tugboat crews, saying a further mediation hearing is set for May 20.