Unions are required by Australian law to give companies seven days’ notice in advance of any industrial action, but can still elect to call off any action before then.

The strike threat escalates a long-running dispute between Woodside and workers over pay and conditions on its North West Shelf gas platforms, which feed Australia’s biggest LNG plant.

The Offshore Alliance, which combines the Maritime Union of Australia and the Australian Workers’ Union, said in a Facebook post today that it had “unanimously endorsed” giving Woodside seven days’ notice to strike if its bargaining claims are not met by close of business on Aug 23.

“They will lose (billions) of LNG export revenue if they take us on, as our members are up for the fight,” the post said.

Some 99% of Woodside workers permitted unions to call a range of industrial action, including work stoppages, after Australia’s industrial umpire, the Fair Work Commission, permitted “protected industrial action” to go ahead.

The Offshore Alliance is also representing workers at Chevron’s Gorgon and Wheatstone LNG facilities. Workers there on Friday began voting on whether to permit unions to call for strike action, with the first results due by Aug 24 at the latest.

Together, Woodside and Chevron’s facilities supply about 10% of the global LNG market, and concerns about a strike have spurred volatility in European gas prices over fears the move would fuel competition between Asian and European buyers for cargoes.