A teenager demanded that a victim hand over his rucksack as he walked through Little Paxton Nature Reserve.
The boy approached the 16-year-old victim as he walked between Mill Lane and Gordon Road at about 11.30am on Monday (May 5).
He stepped in front of him and demanded that he hand over the rucksack. He did not hand it over and when he demanded it again, there was a scuffle and the victim managed to run away.
The would-be thief was described as white, 16 to 17, and had dark brown hair which was long at the front. He wore a black hooded top with the hood up and black tracksuit bottoms with logo writing down the side of the legs.
DC Liz Cooper, who is investigating, said: “As it was a Bank Holiday there were probably people around at the time. I would like to speak to anyone who saw the incident or recognises the description of the youth involved.”
Anyone with information should contact DC Cooper on 101, or Crimestoppers, anonymously, on 0800 555111.