The former chairwoman of the Referendum Council says she is "distressed" and "deflated" by the Prime Minister and Opposition Leader's "disrespectful" behaviour at the Garma festival in Arnhem Land.

"They will do anything and everything except talk to us," Pat Anderson said.

Ms Anderson, a prominent academic, led the Referendum Council which consulted widely with Aboriginal and Torres Strait Islander people on constitutional change.

Last month, the council delivered its report recommending a referendum be held to establish a First Nations assembly to advise the Federal Parliament.

At a convention in May, 250 leaders released the Uluru Statement from the Heart calling for a referendum and, ultimately, a Makarrata — a Yolngu word for a treaty.

Sorry, this video has expired The Uluru Statement from the Heart was delivered by Indigenous leaders in May

At the Garma festival in north-east Arnhem Land on Friday, Prime Minister Malcolm Turnbull said he looked forward to understanding "what Makarrata means".

He delivered much of his speech in Yolngu Matha.

"We know that from little things big things grow," he said.

Opposition Leader Bill Shorten said he would carefully consider the call for a constitutionally-enshrined Indigenous voice to Parliament.

"I understand that people feel politics has failed them and I think people have the right to be cynical, disappointed and perhaps frustrated with the lack of progress in the past," he said.

The leaders' speeches followed a rare address by the land rights champion Dr Galarrwuy Yunupingu who cautioned politicians that Indigenous people expected they would come to Garma for "serious business".

"We live side by side, but not yet united," Dr Yunupingu said.

Bill Shorten wrote to the Prime Minister this week suggesting a joint parliamentary committee to finalise a referendum question. ( ABC News: Mitchell Woolnough )

Ms Anderson said she was deeply disappointed neither Mr Turnbull nor Mr Shorten had accepted the Uluru Statement's recommendations.

"We have nothing more to give you," she said.

"We give you a ceremony, and our leaders didn't get it, they can just stand here and give empty platitudes."

Mr Shorten wrote to the Prime Minister this week suggesting a joint parliamentary committee be established to finalise a referendum question.

But Ms Anderson said that was unnecessary.

"We need another committee like a hole in the head," she said.

"We're living in a Monty Python.

"They didn't respond to the expert panel [on constitutional recognition], they didn't respond to the parliamentary committee."

One of the performers at the Garma festival in north-east Arnhem Land. ( ABC News: Mitchell Woolnough )

At Garma, Cape York author and lawyer Noel Pearson said an Indigenous representative body could be a "persistent and belligerent voice" to advocate for First Nations people.

"This is our country; we want to have a say," Mr Pearson said.

"We've had a failure of leadership so far.

"We've got to get organised and we can't yield to poor leadership."

Constitutional lawyer and University of New South Wales law professor Megan Davis spent six months consulting with Indigenous people in every state and territory earlier this year.

"What we did hear at the dialogues is that people have had enough," Professor Davis said.

"People said that bureaucrats in Canberra control their lives.

"If we have another select committee [on constitutional recognition] that will be five committees in five years."