By Rebecca Carmody for ABC News
Unions have escalated their dispute with Alcoa over foreign workers by blocking the road into the company's WA refinery in Pinjarra for more than three hours.
The WA branch of the Maritime Union led the protest this morning after 40 of its members were told last week they were being replaced by a foreign crew.
The action was timed to coincide with a shift change, preventing several hundred workers entering and leaving the plant, and causing traffic to back up for several kilometres.
Protesters ended the blockade when police arrived and asked them to move on.
Alcoa is selling its ship MV Portland, which has hauled alumina from WA to Alcoa's aluminium smelting plant in Portland, Victoria for 27 years, and replacing it with a foreign flagged vessel and foreign crew.
The company said the ship was nearing the end of its operating life and the decision to replace it with a "more cost efficient method of delivery" would save more than $6 million a year.
The vessel is currently stranded in Portland, with MUA members conducting a 'sit in' and refusing to sail its final voyage.
Emergency hearing to be held into dispute
The Fair Work Commission is holding an emergency hearing into the dispute on Saturday.
The State Secretary of the Maritime Union in WA Chris Cain said what Alcoa was doing was an "absolute disgrace".
"Alcoa should be ashamed of themselves bringing in foreign labour on a domestic route," he said.
"They're sacking Australians and replacing them with cheap, exploited foreign labour.
"This is the first round of a long battle with Alcoa and we won't be walking away.
"We've never ever stopped that ship in 27 years. We've worked with Alcoa and this is the thanks we get, Australians losing their jobs and bringing in foreign labour.
"It's an absolute disgrace and the Federal Government should really look at themselves and say why are we doing this?"
Alcoa said it applied for, and was granted a temporary licence under the Coastal Trading Act 2012, for 17 voyages using a foreign flagged vessel to transport alumina between WA and Victoria for one year.
The MUA claims the foreign crew will be paid as little as $2 per hour.
Alcoa said the foreign crew would receive at least the minimum mandated salary under the International Transport Federation Award.
In a statement, Alcoa said it was considering its legal options in relation to the blockade.
"Alcoa is very disappointed with the union action this morning in mounting a blockade on the private access road to the Pinjarra alumina refinery," it said.
"While production at the refinery was not impacted, night shift workers were prevented from leaving for at least 1.5 hours after the end of their 12 hour shift and traffic was disrupted on both Alcoa's private road and the South West Highway."