The federal government will provide a $220 million loan towards developing a fertiliser plant which has divided Indigenous custodians in Western Australia.

Resources Minister Madeleine King says the Perdaman project, near Karratha in the Pilbara region, will be “transformational” for WA.

It is expected to support a peak of more than 2500 construction and operations jobs during its 40-year life, providing an $8.5 billion public benefit.

The loan, provided under the Northern Australia Infrastructure Facility, will be released when all regulatory approvals and financing conditions have been met.

It comes just weeks after Environment Minister Tanya Plibersek appointed an independent reporter to conduct a full cultural heritage assessment of all industry on the Burrup Peninsula.

The review was requested by Murujuga traditional custodians Raelene Cooper and Josie Alec, who are campaigning against the multibillion dollar Perdaman development because they fear it will damage sacred rock art.

There are believed to be more than a million petroglyphs on Murujuga country dating back over 40,000 years.

The minister will decide, upon receiving the report, whether to grant long-term protection of the relevant area under federal heritage laws.

Ms Cooper said the timing of the loan announcement was “bizarre” and the funding would be better spent on moving the plant.

“This bailout from the federal government is aimed to reassure investors who are spooked about supporting a project that will remove sacred Murujuga rock art over the objections of elders,” she said in a statement on Friday.

Ms Plibersek previously rejected a separate application for a 60-day moratorium on works.

She recognised the Murujuga Aboriginal Corporation and their Circle of Elders as the most representative organisation on cultural knowledge for the five traditional owner groups in the region.

Perdaman has said the project is being thoroughly assessed and will have minimal impact on rock art.

The federal government has also helped fund infrastructure servicing the project, including a $160m loan for a new multi-user wharf and facilities at the Port of Dampier.

Ms King said it would be Australia’s largest urea plant, providing local farmers with secure access to fertiliser that was vital for food security.

“Australia currently imports around 2.4 million tonnes a year of urea for agricultural use, and the Perdaman project will have the capacity to reduce imported volumes,” she said.

“The project has been designed using the best available technology to minimise emissions, with reductions to be achieved in the short to medium term through efficiency gains and solar power imports.

“The project has committed to net zero by 2050, with an aim to achieve a 45 per cent reduction by 2030.”

– AAP