The Australian Workers Union (AWU) says an industrial dispute in regional South Australia may cause delays to the country's oil and gas supplies.
Workers at Santos' Point Bonython port in the Upper Spencer Gulf have been refusing to connect and disconnect oil tankers and gas carriers since late last year.
AWU South Australia assistant secretary Gary Henderson said the work stoppages could cost Santos.
"It could have an impact on domestic gas supply and commercial supply as well because there's not as much gas getting out to the domestic and commercial market because of the work stoppages put in place at Point Bonython and the Cooper Basin," he said.
"I don't think it will have an impact on prices. I think it will have an impact on how much money Santos make."
Port Bonython is a deepwater port near Whyalla that Santos uses to export oil and gas extracted from the outback.
Its workers are striking alongside other Santos employees in the Cooper Basin as part of negotiations for a new enterprise bargaining agreement (EBA).
Demands for pay to reflect CPI
Mr Henderson said the union was pushing for a 5 per cent per year pay rise, or a pay rise linked to Consumer Price Index (CPI) increases, backdated to July 2020, as well as protection of entitlements in the current EBA.
"The workers under [the current] agreement haven't had a wage increase since July 2020," he said.
"We've been negotiating a long time now, around about 18 months. Two enterprise agreements have gone to the workers that have been knocked back by the workers."
Mr Henderson said Santos workers were willing to stay on strike for as long as it takes.
"The workers are quite adamant that they’re going to fight until the end," he said.
"We've been in this for now a year and a half so they're quite keen to keep this up for as long as it takes."
Santos with 'contingency plans'
A Santos spokesperson said it had ways to mitigate any impacts the industrial action might have on supplies.
"Santos is committed to delivering safe and reliable gas to our customers and have contingency plans in the event of industrial action to limit any impact to supply," they said.
"We are committed to ongoing negotiations in good faith with the AWU, AMWU [Australian Manufacturers Workers Union] and employee representatives in order to reach a mutually agreeable outcome for all parties."
