Celebrities such as British business magnate Sir Richard Branson have joined the fight to stop a Norwegian oil company from drilling the Great Australian Bight.

It follows a number of ‘Fight for the Bight’ demonstrations held across Victoria and South Australia, led by surfers and environmentalists who fear the drilling could cause a “catastrophic” oil spill.

Oil giant Equinor is confident that its exploratory drilling will not cause a spill, but its own disaster-mitigation strategy showed that if its plans fail then oil could spread across the south coast of Australia and Tasmania.

The federal government, meanwhile, has thrown its support behind Equinor’s plans, arguing that exploring for oil in the Bight could boost Australia’s fuel security and create jobs.

But hundreds of activists believe the risk of damaging the Bight’s unique marine environment is far too great – and now their concerns are spreading around the world.

An independent group of global leaders, who call themselves ‘Ocean Elders’, has written a letter to Prime Minister Scott Morrison and Opposition Leader Bill Shorten calling on them to intervene and stop the drilling from going ahead.

“If we are to meet the Paris Climate Accord to limit global warming to less than 1.5 degrees, it is essential that we do not open up new fossil fuel reserves, let alone in extremely dangerous and high conservation value environments such as the Bight,” the letter reads.

“Due to the depth and roughness of the seas in the Bight, and the absence of knowledge about pressure and temperature beneath the sea-bed, the likelihood of an accident is higher than in existing oil basins.”

The letter has been signed by Nobel Laureates and high-profile leaders including the Prince of Monaco Albert II, Virgin Group founder Sir Richard Branson and United Nations Messenger of Peace and renowned anthropologist Dame Jane Goodall.

The group wants a permanent ban on oil exploration in the Great Australian Bight, which is home to more than 30 species of whales and dolphins and more unique biodiversity than the Great Barrier Reef.

Unique marine animals such as sea lions live in the Great Australian Bight. Photo: Greenpeace Australia Pacific

Greenpeace Australia Pacific CEO David Ritter said the proposal to drill oil “somewhere as precious as the Bight just beggars belief”.

“The Great Australian Bight is a national and global treasure we can’t afford to risk,” Mr Ritter said.

“And climate change is already an emergency – we cannot afford to open up new oil fields that would push us closer to global catastrophe.”

Australian offshore oil and gas regulator NOPSEMA is in the process of deciding whether to allow Norwegian oil company Equinor to proceed with deep-sea drilling in the Bight.