A new report calls on the National Disability Insurance Scheme to step up support for mentally ill participants.

The National Disability Insurance Scheme isn't doing enough to support mentally ill Australians, a new report says.

There's growing concern about lower-than-expected numbers of people with psychosocial disabilities moving to the scheme, the National Mental Health Commission says.

Even those who get there aren't necessarily receiving the help they need and some are turning to emergency departments instead.

"Participants are not always getting the support they need, and this is leading to a deterioration of individuals' mental health and a greater reliance on clinical mental health services, including presentations to emergency departments," the commission's report said on Monday.

Delays in getting NDIS plans or having them reviewed were also keeping people in hospital for longer, the commission found.

About 64,000 people with psychosocial disabilities had been expected to use the scheme once it was fully up and running.

As of June 30, 25,192 people were on it because of a mental illness, making up nine per cent of participants.

The commission is increasingly concerned that fewer people than expected are moving from Commonwealth community mental health programs to the NDIS, and wants federal funding for the former extended until 2021.

It also wants the NDIS to release data about outcomes for participants with psychosocial disabilities, as well as more government support for mentally ill people who aren't eligible for the scheme.

Also on the commission's wishlist is better coordination of mental health services across states and territories, and more thorough data on what works - and what doesn't - for those in the broader system.

It wants to see a national suicide prevention plan for Aboriginal and Torres Strait Islander people, who suffer a suicide rate twice that of non-indigenous Australians.

FACTS ABOUT MENTAL ILLNESS:

* One-in-five Australia will experience a mental illness each year.

* In 2017, 3128 people took their own lives. Ninety-eight of those were children.

* The suicide rate in Aboriginal and Torres Strait Islander communities is twice that of non-indigenous people.

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