Workers at Inpex's Ichthys liquefied natural gas plant in Darwin have overwhelmingly backed a new pay deal that unions hope to replicate across Australia's offshore energy sector.

The agreement is the first in what unions describe as a second wave of bargaining across the sector, as they seek similar pay and conditions in upcoming negotiations with Shell, Chevron and Woodside Energy.

The Offshore Alliance, comprising the Australian Workers Union and Maritime Union of Australia, and separately the Electrical Trades Union spent months negotiating the deal with Inpex on behalf of about 470 workers.

Deal follows strike. Under the agreement, workers will receive annual pay rises of 3.75%, lifting the maximum base salary for some highly skilled employees to more than A$300,000 ($209,400) by 2030, not including five figure on- and offshore allowances, overtime, travel allowances and bonuses, according to documents seen by media.

Inpex Senior Vice President Corporate Bill Townsend confirmed the vote in an emailed statement and said the company was preparing to submit the agreement with the Fair Work Commission for approval.

Shell's Prelude floating LNG facility is expected to be the next major bargaining battleground, unions said.

The previous Ichthys agreement was signed in 2022.

A strike that halted production and LNG exports ended in June after the two sides reached a provisional agreement, which unions then put to members for ratification.

Inpex unsuccessfully sought to halt the industrial action, arguing that lost production would harm Australia's economy. The Fair Work Commission rejected the application after a two-day hearing.

Industrial action at Chevron's Wheatstone facility in 2023 tightened global LNG supplies, underscoring the impact labor disputes can have in Australia, the world's second-largest LNG exporter.

Unions said the Ichthys June strike caused two condensate cargoes and one LNG cargo to miss scheduled loadings and estimated the disruption cost Inpex about $200 MM in lost earnings at the 9.3-metric MMtpy facility.

The agreement also includes enhanced travel, accommodation and redundancy benefits, and limits the use of contractors and labor-hire firms in ways that could undermine permanent employment, according to a summary of the deal seen by media.

($1 = 1.4327 Australian dollars)