European natural gas prices jumped as workers serving a key export project in Australia prepare for a strike if no deal is reached in pay talks on Wednesday.

Benchmark Dutch front-month gas soared as much as 18% to €42.90 a megawatt-hour in early Monday trading. The industrial action could start as early as Sept. 2 if Woodside Energy Group Ltd., the operator of the plant, doesn’t offer a suitable agreement, unions said over the weekend. That’s in addition to Chevron Corp.’s plants, where workers started voting on potential strikes last week.

The possibility of supply disruptions in Australia, which may impact 10% of global LNG exports, has kept European traders on edge this month. Anxiety has surged even though the continent is well-stocked for winter and it rarely receives fuel from Australia.