Workers at the Inverness yard owned by construction company T. M. Fraser had no idea what was in the sealed storage container which could have been lying on the site for 12 years.

Debris flew into nearby gardens and the area was sealed off for several hours and local residents evacuated to a nearby community centre before the Royal Logistics Corps bomb disposal unit from Edinburgh removed the quarry-type detonators.

The Inverness Courier reported a worker was attempting to open the sealed container with a power saw and he suffered facial injuries.

Inverness Central Councillor Peter Corbett said it was an alarming incident and called on the Health and Safety Executive to highlight to construction companies the danger of detonators stored in their yards unbeknown to them.

He said: “I would like the HSE to start sending out memos to all the building companies to check their premises if there is any explosive material there and also give advice.”

The bomb disposal unit carried out a controlled explosion following the incident.

A police spokesman said: “Our inquiries are still ongoing and the bottom line was that the detonators had been there for some considerable time, perhaps 12 years.”