Three Dunedin Pizza Hut workers have resigned in protest after ''disgusting'' actions by a franchise owner who allegedly served expired food which had been thrown in a skip, extended expiry dates of chicken and seafood, and refused to fix a broken mixer which leaked engine oil into dough.

Restaurant Brands said it was aware of the issues and was working through them as a ''matter of urgency'', and the Ministry for Primary Industries is investigating.

The franchise owner has denied the claims.

Hayley Bevin, 26, quit her job of seven years at Pizza Hut in Dunedin about three weeks ago after what she describes as a series of ''disgusting'' actions by the franchise owner.

Dunedin has two Pizza Hut stores, one in Hillside Rd, South Dunedin, and another in Great King St, North Dunedin.

Naveen Malhotra took over the two franchises of the chain about three months ago, and the hygiene and staff treatment ''kept getting worse'' after that, Bevin said.

He extended best-before dates on food, including chicken and seafood, she said.

A bag of chicken at a Dunedin Pizza Hut which allegedly had a new expiry plastered over the old date. Photos / Hayley Bevin

The workers were told to use ''disgusting, crusty'' expired dough.

He also refused to fix a mixer which was leaking oil into dough, she said.

The last straw came when expired brownies which she had thrown in the skip were put back in rotation, she said.

''I came back on Monday and they were in the chiller. I knew it was the same packet, because I took a photo of it before I left.''

She wanted to warn the public about the practices there.

''I don't want my friends to buy from there and get sick.''

When Bevin resigned, she and two other employees had a meeting with the area manager about the issues and were told they would be investigated.

About two weeks later, she had not heard anything.

''It's like they're trying to protect the brand.''

A dough mixer leaking oil

Nikita Lloyd, 20, who worked at Pizza Hut for four years, left her job at the South Dunedin franchise last week.

''It's just disturbing. I hope my family doesn't go there to get food poisoning.''

She recalled one instance when she wanted to dispose of chicken wings which expired that night.

The duty manager called the franchise owner, who instructed them to put the bag back in the fridge and change the expiry date.

They were used the next day, she said.

In another instance, frozen shrimp were thawing in hot water in a container and had partially cooked and were later put back in the chiller.

Her friend at the North Dunedin store recounted a similar story in which they could smell the expired shrimp, but it was still put on a pizza, she said.

''I just hope something is done.''

Former employee Cory Cairns, 21, said he had seen incidents such as the other two described.

He also recalled an instance when Lloyd received a warning because she argued against using red capsicum, which had fallen on the floor, on a pizza.

Restaurant Brands general manager of marketing Geraldine Oldham said the company was aware of the issues raised.

''Our quality assurance team are working through them as a matter of urgency with the franchise owners of these stores.''

The company did not respond to questions about when it was notified about the issues or what action it would take.

The franchise owner, Malhotra, who said he was overseas, denied the claims.

The staff left because of ''roster problems'', he said.

He did not want to comment further and referred questions to head office.

A Dunedin City Council spokeswoman said it received a complaint about the restaurants on Saturday.

It was referred to the Ministry for Primary Industries, as Pizza Hut chose to be registered through the ministry rather than the council.

A ministry spokeswoman said it was investigating the allegations.