Environmental groups have vowed to continue the fight to block the drilling of an oil exploration well in the Great Australian Bight.

The drilling program by Norwegian energy group Equinor is a step closer after the company was granted approval for its environmental plan.

The decision from the National Offshore Petroleum Safety and Environmental Management Authority has been welcomed by the South Australian and federal governments and the energy sector.

But the Wilderness Society and Greenpeace say they will continue to fight the proposal.