Key points:

Equinor said its exploration plan was "not commercially competitive"
Drilling has been fiercely opposed by environmental groups who warned about a catastrophic spill
The Federal Government is disappointed but supportive of future drilling

The company said it had concluded that its exploration drilling plan was "not commercially competitive" compared with other exploration opportunities.

In December, Equinor was granted environmental approval to drill 372 kilometres south of the Nullarbor coastline, despite protests from environmentalists.

BP abandoned plans to drill the bight in 2016, with Chevron following suit in 2017.

Equinor, which had planned to drill at a depth of 2.5 kilometres, said it made its decision after a "holistic review of its exploration portfolio".

Equinor Australia company manager Jone Stangeland said the venture was simply too expensive.

"We have received bids for the drilling rig, the helicopters, the supply base — the cost for these activities is just too high and too expensive to go ahead and drill the well," he said.

He said the company would "engage with the federal and state authorities regarding our decision to discontinue the exploration program".

Full story: ABC