Health Minister Andrew Little is defending the Government's record on acute mental health as it invested $100 million into new specialist mental health services in Budget 2022.

Speaking to Q+A's Jack Tame, the Health Minister admitted that the Government hadn't made enough progress on acute and specialist mental health services since its first wellbeing budget in 2019.

"We haven't made as much progress as would have liked with the acute and specialist end of mental health. That's why in this budget, we've put $100 million to do that," he said.

"We've got workforce to build, and that's challenging. We've got crisis teams we have to increase and we will do that. We've got child and adolescent mental health services that we have to beef up as well, all of that we can now do with the $100 million we have."

He said the budget's new investment into specialist mental health services would specifically address shortcomings in acute services identified by the Mental Health and Wellbeing Commission in its report in March.

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The commission had found pressure on specialist mental health services, alongside long wait times, despite the Government's earlier investments in mental health services.

"The Mental Health and Wellbeing Commission's report, earlier this year, was really focused on specialist and acute services. And they are right, not a lot has changed," Little said.

He said the Government's $1.9 billion investment into mental health during its first wellbeing budget in 2019 had been focused on closing the "biggest gap" in services.

"The investment we made in 2019, was focused on where the biggest gap was - people who don't need to see a psychiatrist, people who aren't acutely unwell, but who need help with the mental health issues that they've got."

Little admitted there are gaps in the system which he said are "variable across the country".

"The thing about child and adolescent mental health is that it is kind of the specialist end of a specialist field. And so we work pretty hard to recruit these very highly specialised people into that particular area.

But Little couldn't say how many specialists needed to be recruited.

"I can't give you a number of how many we will need. We have a number of vacancies at the moment. What I look at is the waiting times, the time taken for young people to get to see a specialist," he said.

"We know that, for young people, less than a third get to see a specialist within two days of referral. Compare that to adults, and it's roughly two-thirds get to see a specialist within two days. That is not right for kids. A kid's idea of time is way more constrained than an adult's."

Some in the sector, like the Mental Health Foundation's Shaun Robinson, have said the Government's previous investments had only led to incremental delivery.

"Not much has changed for many people at all. We really have not got the systematic change that we're looking for and a lot of time has been wasted," Robinson told Breakfast in April.

READ MORE: Mental health advocate: 'Not much' improvement despite $1.9b

Little said the Mental Health and Wellbeing Commission had earlier found the Government made "good progress" in primary mental health care since 2019. The Health Minister said he believed mental health services were meaningfully better compared to three years ago.

"When we got the He Ara Oranga report in 2018, it said the biggest gap is in frontline mental health services for those with mild-to-moderate mental health issues… and we've now got nearly half of the enrolled patient population who have access to services. And we're doing the rest over the next two-and-a-half years."

He Ara Oranga was the Labour-led government's 2018 inquiry into mental health and addiction.

The Health Minister said addressing mental health issues while they were at a milder stage meant fewer people needing to use acute and specialist services.

"We've started with the frontline mental health services, we're now going to acute specialist services, and we'll make a difference there too."

Stricter regulation of alcohol sales was also a finding of He Ara Oranga in 2018.

Little said the Ministry of Justice and Ministry of Health would be working on a review of New Zealand's current alcohol legislation.

But recommendations from the review are only expected to come forward "partway" through 2023.