UPDATED: 12.44PM Almost 300,000 New Zealanders are waiting for elective surgery with more than half not even on waiting lists.

New research commissioned by health insurers and private hospitals has found the numbers are higher than Ministry of Health figures.

It shows the number of people waiting for surgery is the same as three years ago despite funding increases.

There are 110,000 people on official waiting lists, while 170,000 aren't - even though they've been told they need elective surgery.

Health Funds Association CEO Roger Styles said it's concerning people are waiting around 300 days mostly for public surgery, up by 80 days.

He said the wait for those who have had private surgery is almost 76 days compared to 177 days in the public sector.

Canterbury is leading the national average of unmet surgery needs with thousands left off waiting lists.

Canterbury Charity Hospital Trust chairman Dr Phillip Bagshaw said around 10 per cent in the region aren't on a list because many can't afford to visit their GP.

"It's likely that the block in Canterbury is a higher level of people not actually accessing primary care and therefore not being considered even for secondary care."

Dr Bagshaw said the Ministry of Health isn't looking at the issue properly.

"The government figures really are irrelevant. We know that a large proportion of people aren't seeing their GPs and the GPs aren't referring people on frequently because they're told by their District Health Boards that they don't see and treat those people."

CDHB CEO David Meates said they're reaching Ministry of Health targets.

"There will always be an increased level of demand. How Canterbury is continuing to do it's range of elective surgeries is nothing short of remarkable, because we continue to work in a really earthquake-damaged and facility-constrained environment."