A Kiwi Muslim man and frequent Better Burger customer was alarmed over the weekend to discover the Auckland burger chain cooks its 'halal' meats on the same grill pork products.

Aucklander Raz Domingo, who ordered a burger at Better Burger's Vulcan Lane store in central Auckland, says cooking halal certified meat on the same grill as pork defeats the purpose of serving halal meat - as it allows for contamination.

Domingo, like many practising Muslims, does not eat pork so he was shocked to see bacon on the grill cooking next to the beef burger patty he ordered.

Domingo questioned staff about the cooking practice and was told one of the grills was not working which is why the meats were being cooked on the same grill.

"I took it on face value, so we decided to go to another Better Burger because surely all of the stores wouldn't have the same issue at the same time, and then at the other store they just turned around and said; 'No, that's just their process and what they do'."

Domingo said Better Burger previously never sold pork so it was not a concern he had.

"Had I not asked the question I would have been none of the wiser, and that doesn't sit well with me."

It is hard to come by fast food operators serving halal meat in New Zealand so for the past few years Domingo and his family have been going to Better Burger.

"The only reason we eat there is because we were told at the beginning that they were halal and their menus were halal. Yes their meats are still halal, however, once they contaminate it by cooking it on the same grill it [defeats the purpose]."

Domingo said he would no longer buy food from Better Burger.

"I am disappointed because I enjoyed their burgers.

"There will be lots of other Muslims that are going there thinking they are eating halal food which is not really."

Most takeaway stores and restaurants that sold halal meat only served halal food and did not sell bacon, or in the rare occasion that they did they could ensure there was no cross-contamination between meats, Domingo said.

But Josh Harre, operations manager for Better Burger, said while the chain sourced Halal certified meat from its supplier, it did not advertise that it was halal.

However, Better Burger is regarded as halal in a number of online food directories including on the Heart of the City directory, which says "we have it on authority that the meat is halal" and is listed on the website as "Have Halal, Will Travel".

Harre said Better Burger tried where it could to cook its pork separately but in some sites such as its two Auckland city stores only had one grill due to the smaller shop size.

"The butcher that we use is halal certified and that's the information we share with customers. Given the kitchen layout of our different restaurants, the one at Sylvia Park, Mt Eden and the Airport all do have a separate grill for bacon.

"The two sites in the city, purely based on the layout, don't and that's why we don't advertise [halal] as a brand message," Harre said.

He said there were no signs displayed in Better Burger sites showing its halal supplier certification or branding that advertised Better Burger being halal.

"In the very first store, six years ago it may have been [advertised] as halal, the store that was in the Britomart Country Club but it is now closed."

Harre said Better Burger would look into introducing policies to ensure there was no cross-contamination between meats when cooking food. "Our two most recent stores have certainly endeavoured to do that ... Sylvia Park and Mt Eden are our two most recently built restaurants as well as the one out at the airport and all have those cooking facilities to make sure that it is separate - it is certainly the direction of the brand to be all encompassing and welcoming to everyone."

He said all future Better Burger restaurants would have two grills to keep cooking of the meats separate.

Restaurant Association chief executive Marisa Bidois said any business that advertises or claims to serve halal meats must ensure that the correct practices are followed: "If they cannot, they should not offer the option."

Better Burger operates five fast food restaurants in Auckland.

What is halal meat?

Halal means 'permissible' in Arabic.

Halal food adheres to Islamic law, defined in the Koran, which involves the animal being killed through a cut to the jugular and out of sight of other animals. Animals must be alive and healthy at the time of slaughter. The blood is thereafter drained from the carcass.

During the process, a Muslim prayer known as tasmiya or shahada is recited.