A couple were told to stop kissing or leave a supermarket when a customer complained the display of affection was “disgusting”.

Protesters are now planning a demonstration outside the Sainsbury’s store in New England Street, Brighton, tomorrow to vent their anger on National Coming Out Day and police are investigating the incident as a hate crime.

University of Sussex student Annabelle Paige said she was giving her girlfriend a “light kiss” when the couple visited the New England Street store on Saturday.

However, a mother complained about the pair to a security guard, who told them to stop kissing.

Ms Paige, 22, said: “I thought she was joking. I’ve never experienced something like that. There were heterosexual couples in the store being as affectionate, if not more so.

“I’m so shocked and upset. The customer was essentially being homophobic. The guard didn’t seem to understand that. I was absolutely humiliated.”

Sainsbury’s has since apologised and offered Ms Paige £100 to donate to the charity of her choice – which she has accepted.

A spokeswoman said: “This should never have happened. It is clear Miss Paige and her partner were not behaving inappropriately and we are very sorry they were treated in this way.”

She said the female security guard is employed by a security company and has been told to refer all such complaints to a Sainsbury’s senior manager, who would not have taken action.

The university’s students union said it was appalled by the incident and has organised ‘The Big Kiss In’ outside the store at 6pm tomorrow.

Rianna Gargiulo, welfare officer at Sussex Students’ Union said: “This event did not occur in isolation, our society continues to discriminate against the LGBT community.”

She branded the complaining customer’s actions “shameful” and “offensive”.

She said: “This is a deeply worrying sentiment. The students’ union and the university are here to support all students who face discrimination in our community.”

Ms Gargiulo called on the supermarket giant to increase its donation substantially to show it was serious about tackling homophobia.

Sussex Police hate crime sergeant Peter Allan said he was investigating the incident and was disappointed it happened, especially during national hate crime awareness week.

Anyone affected by the incident can visit sussex.ac.uk/studentlifecentre.