West Mercia Police said they had received two reports of similar incidents involving resurfacing work in Marlbrook near Bromsgrove and Kidderminster.

The incidents happened on December 10 when the men offered to carry out resurfacing work and then aggressively demanded large amounts of cash on completion.

Officers are concerned that some might feel intimidated by the cold calling 'traders' offering to resurface car parks or paths by claiming to be 'in the area' or to 'have left over tarmac they need to use up'.

Police Sergeant Dan Townsend from Kidderminster Police said: "We are investigating these reports of rogue resurfacing workmen who have cold called at a haulage firm and a pub using threats to try and extort money out of businesses for shoddy or unwanted work.

"We would advise people to avoid dealing with anyone who visits their premises uninvited. You should not feel bullied, threatened, or pressured into buying anything or having any work done."

The first incident happened at a haulage firm on Birmingham Road in Marlbrook at around 2 pm when the workmen offered to do a small amount of resurfacing for £50 before laying around 20 sqm and then aggressively raising the price to £7,500. 

Despite offering to pay £1,500 for the work, the men reportedly made threats of violence towards the firm's staff and made repeated aggressive phone calls to them.