Labour unions in the offshore gas sector will appeal to federal and state governments, demanding changes to how approvals for projects are granted, amid escalating threats to billions of dollars of investments from legal challenges backed by green activists.

The Australian Workers’ Union and the Maritime Union say the job security of hundreds of workers has become a major concern due to legal challenges that aim to overturn or stall approvals for projects such as Santos’ $5.8 billion Barossa gas project in the Timor Sea and Woodside Energy’s $16.5 billion Scarborough venture in Western Australia.