The fatal mauling of a Hamilton zoo keeper by a tiger three years ago was partly due to cost-cutting and understaffing, according to a WorkSafe report.

Photo: Hamilton Zoo website

Samantha Kudeweh, 43, was killed after entering the tiger enclosure at Hamilton Zoo, unaware the large male Sumatran tiger, Oz, was roaming freely.

The report, which has been released under the Official Information Act, found shifting a gate following a near miss in 2013 meant Mrs Kudeweh could not easily see the tiger's den gate was open.

Zoo management had ruled out realigning the fence to accommodate the new two-gate airlock system - which was intended to be safer - because it was deemed too expensive.

The zoo had also considered painting counter-weights on the gates a distinctive colour, which would have made it easier to tell if a gate was open, but "could not afford the paint".

Keepers interviewed by Worksafe said the zoo was critically understaffed and under-resourced and keepers looking after the most dangerous animals, tigers and chimpanzees, worked alone.

While Auckland and Wellington zoos had a ratio of one keeper per seven animals, each keeper at Hamilton Zoo had the care of 21 animals.

A number of staff told investigators they had heard it said "someone is going to die if changes aren't made".

In his statement, the zoo's director Steven Standley, said he had advised the council that "with the current staffing level, an accident was more likely".

"He however never believed that a fatality would occur."

Hamilton City Council pleaded guilty in June 2016 to failing to take all practical steps to ensure the safety of Samantha Kudeweh.

It was fined nearly $38,250 and ordered to pay $10,000 in reparation to Ms Kudeweh's family.

The council also paid a further $190,000 to a trust fund set up for her two children, Billy and Sage, aged 9 and 3 when she died.