Police say a phone box at Llys Celyn at Trehafren, Newtown was "smashed to pieces" by someone.
The telephone box which is situated along a road and a car park was damaged at around 3.10pm last Friday.
Police say a young white male was using the phone box (pictured before the attack) just before the reported damage.
"We would especially like to speak to a young white male, dressed all in black with short dark hair, who was seen using the public telephone kiosk in Llys Celyn, Newtown around the time before walking off in the direction of the main Llanidloes Road as he may have information that could help the investigation," said a Newtown Police spokesperson.
Anyone who may have witnessed this incident is asked to contact police at Newtown by telephoning 101.