BP's latest environmental plan for its proposed oil search in the Great Australian Bight has failed to win regulatory approval but it will be able to submit a fresh proposal.

The company wants to drill four exploration wells up to 2.5 kilometres deep off South Australia's west coast but regulator, the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), has knocked back BP's latest environmental plan.

It can modify and resubmit the plan by the middle of July, which NOPSEMA said was a normal part of the process.

BP told a Senate inquiry recently it believed it could explore safely and responsibly in the Bight.

It wants to drill about 400 kilometres west of Port Lincoln and 340 kilometres south-west of Ceduna, between late this year and next year.

Environment groups remain opposed to oil exploration in the Bight, citing risks to the marine environment.

Wilderness Society director Peter Owen said BP had put in a substandard application, despite its past record.

"BP was responsible for the world's biggest oil spill accident, the Deepwater Horizon tragedy in 2010, when 800 million litres of oil spewed into the Gulf of Mexico for 87 days," he said.

"One would expect BP to go to great lengths to show the regulator it had learnt from the Gulf of Mexico disaster and submit an application that would far exceed the required standards.

"Instead it again submitted a substandard application in the hope it will be approved."

Sea Shepherd official Jeff Hansen said the Bight would be at risk whatever efforts potential explorers took.

"If BP is allowed to drill for oil in the Great Australian Bight, it's not a question of if there will be an oil spill but when," he said.

The Australian Petroleum Production and Exploration Association said it was confident the Bight could be safely explored as there had been successful work off the coasts of Victoria and Western Australia for several decades now.