Labour's leader says too many people with mental health issues are being discharged from hospital too early - and the result is fatal.

An Auditor-General's report into mental health shows the sector's failing in many cases to implement a proper discharge plan, or follow up on those patients.

And figures obtained by Labour under the OIA on the matter, suggest over 500 outpatients supposed to be under the care of DHBs, died of suspected suicide over the last four years.

Andrew Little said patients are being discharged before they are ready only to be readmitted, or as those figures show, worse.

"People will have died as a consequence of the stress the system is under, inadequate and incomplete treatment that patients have got and being discharged too early."

Mr Little said the report shows this Government doesn't know what it's doing - and demand for these services is quickly increasing.

"You've got a service that is stretched to breaking point. You've got mental health professionals who are stressed out, burnt out and struggling to do their job."

The Health Minister has promised to make sure the Auditor-General's mental health recommendations are on the agenda, next time he meets with the Director-General of Health.

Minister Jonathan Coleman is adamant services are adequately funded and said District Health Boards need to make sure they're taking these recommendations on board.

"Clearly after a public report like that, they'd have to be a bit silly if they weren't clearly able to demonstrate and document their progress."