Starbucks coffee
In this photo, a pair of Starbucks iced coffees are pictured inside a Lower Manhattan store on Aug. 21, 2009. Getty Images

Starbucks authorities have launched an investigation Thursday after one of their workers was alleged to have written 'fat' on an 11-year-old schoolgirl's coffee cup instead of writing her name. The girl named Teigahn Sangster visited the store's branch in Fort Kinnaird, Edinburgh, with her friend.

A Starbucks spokesman told Metro.co.uk: "We are concerned to learn of this as this is not indicative of the friendly service we provide in our stores. We are urgently investigating the matter to determine exactly what happened."

Sangster claimed that the small caramel frappucino she ordered had 'fat' or 'fato' written on the side of the cup in place of her name. This was the first time Sangster went out with her friend alone, unaccompanied by her parents.

Sangster told Metro: "I felt really shocked when I saw what was written. As we sat down, my friend first spotted it and said 'that’s rude.' I felt really embarrassed, upset and angry by it. What if they’d written it for someone who was bigger? They would feel quite hurt by it and think they had a point – it would scar them for life. I’d been excited to go as it was the first time we’d gone on our own and felt really grown up but after seeing what was written I just wanted to go home — it really spoiled it for me."

Sangster's mother Dionne Ford commented on the incident and said she was 'disgusted' by it. She said "I was furious when I heard what had happened – especially on her first trip alone. She phoned me from the cafe to tell me what had happened and I told her to bring the cup home. She told me 'it doesn’t matter mum, I am fat.' It was really upsetting to hear — it made her feel so little and knocked her confidence, I think it’s terrible."

"She’s tall for her age, 5ft 5, and is well developed already but she’s not fat by any stretch of the imagination. She wears adult size eight clothing and regularly goes horse riding and indoor rock climbing – she’s a really active girl. The staff need extra training and if it was done as a personal attack that person should be reprimanded, it’s completely disgusting," Ford added.