It was a moment that saw part of a packed-out auditorium descend into chaos.

Legions of dedicated Elvis Presley fans had turned up to watch a tribute concert on Sunday.

But when one 'burly' fan stood up from his second row seat at the Theatre Royal and refused to sit down again, the evening took a turn for the worse.

People sitting nearby said the man, who was around 6'5 and wearing a pair of Elvis' famous sunglasses, suddenly turned aggressive after being asked to move.

And as the show got under way again after the interval, the man tried to punch an elderly audience-goer in the row behind him, prompting others to get involved.

Susan Bartram, a child minder from Long Stratton, was sitting just one seat away from the altercation, along with her husband and parents.

'It just got chaotic,' the 49-year-old said. 'After he tried to punch the man next to my husband, someone grabbed his hands and then he punched the bloke in front of him.

'Meanwhile, someone sitting behind me tried to jump over my head to get at him, and there were people at least four rows back trying to get involved.'

Despite leaving many fans all shook up, no one was said to have been injured in the incident.

Audience member Margaret Gibbs, from New Costessey, who was with her husband Mike, said people were screaming as the fight erupted, but the show carried on.

'He just went berserk and was starting on people next to him,' she said. 'At one point it looked like he had his hands around someone's throat.

'It was like being down Prince of Wales Road on a Saturday night. People don't expect to go to the theatre and have a fight.'

The incident happened during the 'A Vision of Elvis' show, which was performed by Rob Kingsley.

A Theatre Royal spokesman said the audience member had a medical issue and became 'disorientated' as the altercation broke out.

'The theatre's front-of-house team responded immediately, helped him from the auditorium and called an ambulance.

'Paramedics assessed him and took him to hospital where he could be treated for his medical condition,' the theatre spokesman added.

The theatre said it took the safety and security of its guests 'very seriously' and said staff checked people sitting nearby to ensure they were uninjured.

A police spokesman said officers were not called to the event.