Early morning market-day shoppers in Abergavenny on Tuesday were shocked to see smoke billowing out of the new jeweller’s shop - Pandora- in High Street.

But it turned out to be a false alarm.

Staff arriving for work at around 9am had accidentally triggered the burglar alarm which automatically blanketed the store in a ‘smoke cloak’ - a cloud of thick synthetic smoke designed to disorientate intruders.

Fire officers were quickly on the scene, rolling out a positive pressure fan, which acts like a giant hairdryer to blow the smoke out of the building.

A spokesman for the fire service said, “We knew straight away what we were dealing with. When this kind of burglar alarm goes off it immediately fills the shop floor with thick smoke. It’s a type of alarm that’s normally installed by shops selling high value goods. We deal with several cases like this every year.

“Basically we just open the front and back doors and use the fan to force the smoke outside.”

Sholeh Harris, manager at Pandora, said the smoke cloak was probably activated by a staff member due to a technical fault.

She said, “Pandora has only been open in Abergavenny for three weeks, so we were bound to have a few teething problems with our security, but rest assured it was a simple mistake.”