Burglaries at unoccupied houses in Lincoln prompted Lincolnshire Police to urge landlords, letting agents and property developers to check their vacant properties.
Two unoccupied houses in Monks Road have been broken into, one overnight on April 19/20 and one sometime in the last week.
A number of power tools were stolen from one house and copper pipes from the other.
Police are urging anyone with vacant properties in the city to make them as secure as possible and to check them on a regular basis.
Officers say this is an ongoing issue in Lincoln, with thieves particularly targeting copper due to its current high scrap value.
Call Lincolnshire Police with information on 101, or call independent charity Crimestoppers anonymously on: 0800 555 111.