ADELAIDE, Australia (AP) — A Chevron Corp. liquefied natural gas plant in Australia had resumed full production after a fault cut output by one-fifth for three days amid strike action, the U.S. energy giant said on Monday.

A turbine tripped at the Wheatstone LNG plant in Western Australia state on Thursday last week as around 500 unionized Chevron staff escalated strike action over pay and conditions.

Wheatstone and Chevron’s Gorgon plant, both in the state’s Pilbara region, account for between 5% and 7% of global LNG supply.

Chevron said full production did not resume at Wheatstone until Sunday night.

“During this time, LNG continued to be produced at approximately 80% of usual rates and vessel loading continued,” a Chevron statement said.

“There has been no change to scheduled LNG deliveries,” Chevron added.

Wheatstone produces 8.9 million metric tons (9.8 million U.S. tons) of LNG a year.

About 500 Chevron employees who are members of the Offshore Alliance, a partnership between the Australian Workers’ Union and the Maritime Union of Australia that represents workers in Australia’s offshore oil and gas industry, stopped work for a second consecutive day on Sunday and warned of further disruptions to come.

The union argues that less experienced non-union labor that is filling in for striking union members would lead to a reduction in LNG output and cost Chevron more than the higher wages and improved conditions that are demanded.

The union blamed incompetence of non-union labor for a four-hour delay in LNG being shipped from Wheatstone on Friday.

“It is pretty clear that Chevron’s so-called contingency workforce aren’t up to it,” Offshore Alliance posted on social media on Saturday.

Australian Associated Press reported the turbine fault at Wheatstone was caused by an instrumentation issue unrelated to the strike. The strike action includes bans on mooring tankers and loading them with LNG, The Australian Financial Review newspaper reported last week.

The Offshore Alliance has not responded to requests for comment.