A major mental health group says an NDIS funding change will leave people with bipolar disorder unable to access support.

Mental Health Victoria (MHV) says community support programs are being defunded in order to free up tens of millions of dollars for the NDIS instead.

The group says that just 10 per cent of people who suffer serious and complex mental health issues qualify for the NDIS, meaning many were relying on other programs.

“Individuals will end up having to fall back on the emergency part of the system … and that's really the wrong message that we want to be delivering,” MHV chief Angus Clelland says.

“The ideal is that we treat and look after people in the community.”

MHV also says the funding changes could see up to 1,000 specialist staff lose their jobs by mid-2019.

The National Disability Insurance Agency says the NDIS “was never intended to replace other government support systems, including mental health system or community-based support or treatment for people living with mental health conditions”.

Its spokesperson said NDIS funding will allow more people with mental health issues to access assistance.