Officers trained to deal with exploded ordnance rushed to the Loreny Industrial estate in Kilmarnock following the unexplained find.

A grenade and two cluster bombs had been dumped, all of them dating from the Second World War while people working in firms on the estate carried on their normal day.

Officers told workers to stay indoors as a precaution until the explosives had been dealt with.

Officers from Police Scotland’s bomb disposal team and the Fire and Rescue stayed at the scene until it was declared safe.

The grenade was said to contain explosives, while the two bombs contained phosphorous material.

All three devices were taken from the site in a secure container to be disposed off safely elsewhere.

Police said that it was unknown how the munitions had ended up in the skip, and that they had launched an investigation into their origin.

A spokesman for Police Scotland said: “I can confirm that at 3pm police responded to a report of unexploded ordinance Loreny industrial estate in Kilmarnock.

“An explosive ordnance disposal team headed to the scene with support from the Scottish fire service. As a precaution a number of business in proximity to the device were asked to stay inside their buildings in the meantime while inquiries continued.”

Weapons from the period are occasionally recovered in Scotland, mostly washed up on beaches or found in isolated locations used for the training of troops. In 2012 a rusting mortar bomb was discovered near Reareach Hil l , Glengeoullie, on Cawdor Estates.