A group of First Nations people, including Josie Alec from the Australian Conservation Foundation and Raelene Cooper from Save our Songlines, have written and published a letter to Indigenous Australians Minister Linda Burney, Assistant Minister Malarndirri McCarthy and Lingiari MP Marion Scrymgour.

The letter calls on the federal government to listen to Indigenous voices and claims an amendment to offshore gas legislation is intended to remove their consultation rights to be heard on developments in sea country that affect cultural heritage and songlines.

Flanked by Greens and independent politicians in parliament house on Tuesday, Ms Alec said First Nations people have an obligation to protect land and sea.

"Our law was given to us in the ground and it was given to us for the sustainability and the longevity of all life on earth," she said.

"That means my children and your children and all of our future children to come, with these projects going ahead ... our children and their lives are at stake here.

"These bills that are being put through are trying to silence our voices as First Nations people."

The government has added an "environmental safeguard" to the proposed legislation, enabling both the environment and resources ministers to consider changes to consultation processes.

But independent Senator Lidia Thorpe accused Labor of being hypocritical and looking after their mates in the mining industry.

"This is an absolute disgrace that flies in the face of free, prior and informed consent," she said.

Greens Senator Dorinda Cox also accused the government of colluding with industry to sell offshore leases without traditional owner input.

The letter-writers said the bill would silence their voices.

"When your government says, always was, always will be, that includes the lands and seas that multinational gas companies seek to destroy with their drilling into our seas and the clearing of our lands," the letter said.

"This bill is a betrayal.

"International human rights law recognises our rights to be listened to."

The groups said the government should instead focus on finishing its review of offshore gas consultation processes, including transparency on how it would improve First Nations input.

A spokesperson for Resources Minister Madeleine King said that the bill doesn't change the legal requirements for consultation and that industry must engage with First Nations people in good faith.

"The government's reforms are not about weakening consultation requirements or environmental protections, and amendments moved by the government in relation to this bill insert additional protections that reflect the government's longstanding intention to maintain the integrity of our environmental protection regime," the spokesperson said.

Australian Associated Press