Workers from Taronga and Western Plains zoos will receive millions in back pay after the non-profit admitted to underpaying casual staff.

The NSW zoo operator on Friday said it was acting to address historic underpayments worth about $2.6 million, including interest.

It found it was underpaying casual staff after undertaking a “proactive review” of its interpretation of the relevant award and how this had been applied through a new payroll system, introduced in February 2021.

Taronga chief executive Cameron Kerr said he was deeply sorry to workers who had been underpaid.

“I offer my sincere apologies to those current and former staff who have been impacted,” he said.

Casual staff held a snap strike at Taronga’s Western Plains Zoo in Dubbo last year, complaining the new payroll system had underpaid them and taken away their leave entitlements.

Taronga had incorrectly concluded casual workers were not entitled to a 15 per cent loading on weekdays.

Tony Callinan, NSW state secretary of the Australia Workers Union, which represented the Zoo workers, said members on site were right to stand up to the Zoo’s management.

“It’s a bit rich for Taronga to come out today and claim to be self reporting an underpayment when the payroll audit would have never happened if not for AWU members’ taking action in November 2022,” Mr Callinan said.

“Taronga Western Plains refused for months to accept there was a problem with their payroll system and it was only after AWU members held a stop work meeting at Dubbo that they agreed to meet to us,” he added.

Back payments will be made in July and will include interest of six per cent, and superannuation paid at 11 per cent.

The zoo will also correct its payroll system from July 13.

Managing the introduction of the new payroll system and disruptions caused by the COVID-19 pandemic meant Taronga had not identified the underpayments earlier, Mr Kerr said.

“We take this matter very seriously and we are in the process of notifying all those who have been affected,” he said.

The zoo said independent auditors have been engaged to thoroughly review the extent of underpayments and management were committed to remedying the issue quickly.

– AAP