North Yorkshire Police has issued a warning to businesses in the area after receiving a number of complaints about men offering to sharpen tools.
Since May 5, police say they have received 13 reports from businesses across the county reporting men with Eastern European accents who have attended their premises, offered to sharpen tools, have carried out sub-standard work and intimidated members of staff.
The majority of the offences have been reported over the past three days and involve men travelling, in the main, in Mercedes vehicles.
Other vehicles reported include a Volkswagen Passat, Renault van, Citroen and BMW. In many incidents the men arrived in two vehicles.
Incidents have been reported in Thirsk and its outlying villages, Whitby, Malton, Easingwold, Stokesley, Sherriff Hutton and Sutton on the Forest.
Officers are advising business owners to be on their guard and to contact the police if they have been approached by the men.
They are also appealing to anyone who can help identify the men to contact them.
Anyone with any information who has not already contacted the police is asked to call North Yorkshire Police on 101 and pass information to the Force Control Room.
If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.