UPDATED 9.28am The Accident Compensation Corporation is each year rejecting claims by between 200,000 and 300,000 Kiwis for no-fault, accidental injury compensation, a new report claims.

It says this is more than triple the 70,000 claimants the ACC reports rejecting each year.

The report backed by the Law Foundation and Otago University, says too many people are missing out on injury compensation because the ACC is using a "narrow, legalistic" test to determine whether it will fund a person's treatment or not.

The ACC's policies were also "incredibly complex and difficult to navigate", lead author Warren Forster says.

Unsuccessful claimants who then challenge the ACC's decisions find themselves pitted against a huge, billion-dollar specialist Crown agency, he said.

That undermined the intent of the scheme to help injured people get back up on their feet sooner, he said.

ACC chief executive Scott Pickering said it agrees with the report that its systems and processes are complex and difficult to navigate for customers and our own staff.

“ACC deals with around two million claims every year and our careful and considered estimate, previously given to the Dean Review, was that ACC made 70,000 decisions declining cover or entitlements. And, within that number, many decisions can be made for a client in a year," Pickering said.

“Of those around 6,500 decisions are reviewed. And of those 6,500 reviews, 84 per cent are found in favour of ACC.”

To help the "hundreds of thousands of injured New Zealanders whose claims are declined each year", Mr Forster called for the establishment of an independent Personal Injury Commissioner to oversee the ACC.

"This will better help injured people and, in the long run, it will reduce the economic, social, and personal costs of injury to society," he said.