A vicious inter-union fight has broken out on Western Australia’s biggest construction project, Woodside’s billion-dollar expansion of its Pluto LNG facility, raising the spectre of major industrial disruption when pay talks launch next year.

Since last week, the Offshore Alliance – made up of the Australian Workers Union and Maritime Union of Australia – has been sending officials to organise Pluto 2’s 2000 workers, part of the $12.5 billion Scarborough Energy project, ahead of bargaining for a new agreement.