A relic believed to be a cannonball has been discovered at Broughty Castle in Dundee.

The mystery object was discovered on the site during digging to upgrade the castle's drainage works.

A leading public body is looking into the origins of the relic amid speculation it could be a cannonball fired from the fortress during a conflict.

Historic Environment Scotland plans to contact a ballistics expert to see if they can shed more light on what the object might be.

A spokesperson for the organisation said: "We are currently in possession of a very old object, believed to be a cannonball, which was discovered near Broughty Castle during digging for drainage works.

"Although the castle saw relatively little conflict during its 450-year history, it's very tempting to speculate on whether the object is a cannonball, and if so did it feature in a conflict related to the stronghold?

"At the moment, though, it is too early to be certain whether it is even a cannonball, but our collections team are looking into it."

The spokesperson added: "Either way, it is an interesting discovery."

The historic castle, which sits on the banks of the River Tay, has only been directly involved in military conflicts on a couple of occasions.

Broughty Castle featured in the War of the Rough Wooing between England and Scotland in the 16th century, which saw the stronghold taken into English hands in 1547 before being recaptured by the Scots, aided by the French, in 1550.

In 1651, the castle faced a siege when forces loyal to Oliver Cromwell attacked Dundee and captured its townspeople due to its Royalist stance.

Dundee City Council purchased the site in 1969 and converted it into a museum.