NASTY: A BK Hawaiian Chicken burger sold to a Wellington customer with mould on it.

A Wellington student who was sold a mouldy burger at Burger King was asked by a manager to destroy the evidence.

Tessa O'Malley, 19, unwrapped her Hawaiian Chicken burger early yesterday, after a night out in town.

"We ate our chips and things and then when I opened my burger ... I was kind of shocked. It was disgusting."

The bottom bun was riddled with spores of green and grey mould.

Massey University student Miss O'Malley and her friend took photos of the burger on their phones, posting one image on Facebook.

They then returned the burger to the counter, where the manager became hostile.

"When we went back in we had the burger wrapped up and didn't make a scene. We showed her [the duty manager] and said: 'This is pretty disgusting.'

"She just tried to take it straight away because she obviously didn't want anyone else to see it. [Then] she saw one of our friends had a photo, and said she wouldn't do anything unless we deleted all the photos."

The manager offered a refund and a replacement burger, but only if the women deleted their pictures in front of her. Then she and another employee ordered them out, O'Malley said.

A Dominion Post employee also witnessed a customer return a Whopper to the counter at Burger King's Manners Mall store last week.

The customer had taken a bite from the burger before turning it over and seeing the state of the bottom of bun, which was completely green.

A Burger King spokeswoman said its buns occasionally got mouldy in summer.

"In a spell of warm weather, you get one or two complaints. We find when the weather is warm and humid we do get the odd mouldy bun.

"The use-by date and handling procedures in restaurants are designed to minimise the risk of this happening, but unfortunately in this instance the bun was not picked up.

"We ... have today sent an alert to all restaurants to be extra vigilant in checking buns due to the warm weather."

Regional Public Health, which monitors food compliance, has been made aware of women's complaint and plans to look into it.