Ancient stones used to build Stonehenge are being stolen, police have warned, as one thief used it as a garden ornament.

The thief swiped the bluestone last week from the Preseli Hills in Pembrokeshire, Wales, where some of the stone used for the Wiltshire monument was quarried and transported.

Officers tracked it down to a garden 10 miles away. The person responsible said they weren't aware it was illegal to remove it from the area.

Inspector Reuben Palin said: “This case was quite unusual in that there was actually a witness to the theft, who swiftly started filming while the stone was dug up and put into a car.

“In the past we have had people taking bluestone for the spiritual and healing property it is believed to possess, and in this case a large stone was taken for decoration purposes."

The Preseli Hills are part of the Mynydd Preseli Site of Special Scientific Interest and Preseli Special Area of Conservation.

Local authorities knew bluestone was regularly being taken from the Preseli area but were struggling to work out where it was going. A reminder is now being issued that it is illegal to remove it.

Stonehenge was constructed on Salisbury Plain from two types of stone: 42 bluestones, which are volcanic rock, and the sarsens, the larger standing stones.