The Offshore Alliance said on Monday the union grouping had served notice to strike at Inpex's Ichthys liquefied natural gas facility in northern Australia from May 27, in a move that could worsen already tight global energy supplies.
Last month 326 of 346 union workers at the 9.3 million metric-ton-a-year facility near Darwin voted for strike action over pay and conditions, pending six days of negotiations in May.
Lawyers for the Offshore Alliance, a grouping of the Maritime Union of Australia and the Australian Workers Union, served the Japanese firm with intent to strike at any point from May 27 to June 10, saying months of talks had failed to make any progress.
"We have made it clear to Inpex that we aren’t going to cop the short-changing of our bargaining claims simply because Inpex could not be bothered reading our claims for six months," a spokesperson said in a statement.
The union group has advised Inpex it would continue to bargain with the company at meetings scheduled on May 25 and 26.
Inpex did not immediately respond to a request for comment.
Any disruption at Ichthys LNG could exacerbate already tight energy supplies globally and is being closely watched by Japanese power and gas utilities that are its main customers.
Australia is Japan's largest LNG supplier, and the country is already facing a possible supply crunch due to the Iran war and rising air-conditioning demand as Japan heads into summer.
(Reuters - Reporting by Alasdair Pal in Sydney; Editing by Christian Schmollinger and Kate Mayberry)