Officers are asking those walking in the Clanna area of Lydney, the Forest of Dean to be alert as nails and tacks have been found on footpaths and bridleways.
The nails and tacks were first found at Clanna Weir Mill on the afternoon of Saturday 25 November and a number of additional reports have come in since.
There have also been reports of the items being found in the road causing vehicle tyres to puncture.
The Rural Crime Team are now encouraging local residents and visitors to the area to be aware when on walks as the nails and tacks can cause injuries if stood on.
Anyone with information on the person/s responsible for leaving the nails and tacks behind is asked to complete the following online form quoting incident 217 of 25 November: http://www.gloucestershire.police.uk/tua/tell-us-about/cor/tell-us-about-existing-case-report/