One of the guards yanked at the shoulder strap of the rucksack as he set off the alarms.
The two alarm detectors began to buckle as he tussled with the pair of guards.
The alleged thief – wearing a flat cap – then shoved one of them away.
He screamed: “Get off my f*cking bag.”
The other guard managed to keep a tight hold of the strap so he couldn’t get away.
A member of staff walks over to see what is going on in the supermarket in Lewes Road, Brighton. East Sussex on Boxing Day (26 Dec).
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The two guards – employed by Mitie – then move the man away from the front doors.
But they continue to grapple with the man who then loses his footing and bangs into the wall.
The pair keep trying to get the bag off him.
Shocked shoppers are seen walking by and one filmed it on their mobile phone in a one minute and two second video.
One of the guards says: “What have you got in there?”
The man replied: “Nothing.”
He asked again: “Give me what’s in there and you can go.”
But he wouldn’t let them see what was inside.
One local said: “One shopper took the ‘self-service’ concept a bit too far on Boxing Day.
“Caught allegedly trying to snag more than just holiday deals.”
A Sainsbury’s spokesperson said: “We are investigating this incident.”
A Mitie spokesperson added: “We are investigating the incident.
“And we aren’t able to comment until the investigation is complete.”
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