The interim Productivity Commission report, released on Wednesday, found the National Mental Health and Suicide Prevention Agreement was "not fit for purpose" and had made little progress since taking effect in 2022.
A particular area of failure was the system's inability to deliver on a pledge to develop nationwide arrangements to provide psychosocial supports outside the National Disability Insurance Scheme, it said.
It comprised "a raft of outputs and initiatives that aren't connected to each other or to an overarching strategy", a productivity commissioner says.
"In its current form, it cannot deliver the systemic, co-ordinated change it promises," Selwyn Button said in a statement.
"Consumers, carers and service providers we spoke with told us of ongoing challenges accessing and affording care and of unco-ordinated services that do not respond to need."
Treasurer Jim Chalmers commissioned the review in January, looking into the agreement signed between the federal government and states and territories, due to expire in 2026.
The Albanese government, which has spent more than $2.4 billion on the area since taking office in May 2022, says the review is part of keeping services effective and affordable.
National Mental Health Consumer Alliance CEO Priscilla Brice said the agreement had failed to meet expectations as it was not developed "hand in hand with people with lived experience of mental health challenges".
"We were not included in the development or negotiations for the agreement, nor the ongoing governance or measurement of the agreement," Ms Brice told AAP.
"People with lived expertise need to be involved in the next agreement at both the national level and the state and territory level.
"This would ensure that the people who know the systems best - the people who use mental health services - are at the heart of decision-making."
She urged extra funding for mental health services and advocacy bodies as well as stricter accountability to bolster the system.
Some 22 per cent of Australians have experienced a mental illness in the past 12 months, while 43 per cent will have a mental illness during their lifetime, Australian Bureau of Statistics research shows.
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