The protest took place on Wednesday night at a Sainsbury's in Brighton Twitter @Flreeon

Gay rights activists staged a "kiss-in" at a Brighton branch of Sainsbury's after a security guard told a lesbian couple they were "disgusting" for kissing each other and threatened with expulsion from the shop if they did not stop.

The event, during which dozens of same and mixed-sex couples occupied the store and kissed – including a man and woman in wedding dress – did not disrupt normal practice and shoppers continued around them.

Video footage on ITV News showed a number of people in fancy dress and women holding up signs with customised supermarket-style slogans such as "Live well for lez".

The incident that sparked the protest took place last week, when a customer complained to security about Annabelle Paige, a University of Sussex student, and her partner kissing in the aisle.

Paige told The Times she had only "briefly" kissed her girlfriend, yet the security guard told them to stop because a customer "found it disgusting" and threatened them with expulsion from the shop if they continued.

"I'm so shocked and upset about it", Paige said. "I get that if another customer is uncomfortable that's a bad thing... but the problem is the other customer was in the wrong and essentially being homophobic. The guard didn't seem to understand that, I was absolutely humiliated."

On Thursday 16 October, the University of Sussex's student union tweeted: "Thanks to everyone who took part in the #bigkissin. Great to see people in Brighton and beyond showing we like kissing and hate homophobia."

Sainsbury's took the protest light-heartedly: "We're pleased everyone had fun and we were happy for the change to remind everyone just how important being an inclusive business and employer is to us."

The supermarket chain also apologised for the homophobic comment, saying the guard was employed by a third party and that Paige and her partner were "not acting inappropriately".

Brighton MP Caroline Lucas told the Guardian the kiss-in was a "typically creative Brighton way to highlight the issue".