Witnesses are being sought following the theft on two occasions of lead weights from two lifts in Nelson Court on Lagland Street in Poole.
The first happened at around 12.30am on Saturday 26 November and the second in the evening of Sunday 11 December.
Police Constable Chris Lee, of Poole police, said: “I am appealing to anyone who witnessed any suspicious activity in the area at the time of both incidents to come forward.
“I am aware that CCTV is being installed in the block of flats and the weights are to be replaced with reinforced concrete and not lead to prevent future theft occurring.”
Anyone with information is asked to contact Dorset Police at www.dorset.police.uk, via email email@example.com or by calling 101, quoting occurrence number 55160185873.
Alternatively contact Crimestoppers anonymously on 0800 555111 or via www.crimestoppers-uk.org.