(Bloomberg) -- Liquefied natural gas workers at key Chevron Corp. sites in Western Australia have begun ramping up a campaign of industrial action in a dispute that has roiled global energy markets.

Staff started a program of escalated action Thursday after beginning partial strikes on Sept. 8, and will ratchet up stoppages over the “coming days and weeks,” the Offshore Alliance, a group representing two major labor unions, said in a Facebook post.

It isn’t clear how many hours a day the workers are on strike. Chevron said it has been given notice that workers could commence rolling 24-hour stoppages from 6 a.m. Perth time Thursday. 

“Our focus is on maintaining safe and reliable operations in the event of disruption, and we will continue to manage the range of uncertainties that industrial action may present,” Chevron said in a statement.

Union members at the Gorgon and Wheatstone LNG facilities had previously flagged plans to begin all-day stoppages for a period of as long as two weeks from Sept. 14 if the sides failed to reach an agreement on pay and other conditions.

Under the escalation, the staff could also limit activities including the mooring and loading of tankers or other vessels, laboratory analysis work and restarts of equipment.

The 500 union members are meeting regularly to determine what action to take, according to an Offshore Alliance spokesperson. The strikes could take different forms, from single one-hour walkouts to longer action, and may differ from team to team, he said.

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Though LNG exports haven’t yet been affected, lengthy walkouts increase the risk of disruption. The prospects of lower gas exports from one of the world’s biggest suppliers has sent global prices higher, as it threatens greater competition for LNG during peak demand in the northern hemisphere winter.

Chevron’s requests for a regulator to intervene in the labor dispute will be heard on Sept. 22, and may lead to an end of the stalemate. The company applied for so-called intractable bargaining declarations for the sites, which would potentially allow the Fair Work Commission to decide on terms and conditions of employment.

--With assistance from David Stringer.

(Updates with the union’s statement in the second paragraph.)

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