RAF Whittington has confirmed it sent a team to a Northamptonshire industrial estate.
The incident happened in Tenter Road in Moulton Park industrial estate today and Northamptonshire Police and a Explosive Ordnance Disposal team from RAF Whittington attended the scene.
A spokesman for RAF Whittington said: "The item in question was a Mills grenade dating from around the World War Two period. It has now been destroyed in a controlled demolition."
He urges the public - in any circumstance where they might come across a suspicious item - not to make any attempts to touch it or move it and call the police straight away before an EOD team attends the scene.