A gang of five men attacked a passer-by by pushing him to the ground and robbing him of cash and a mobile phone.
The robbery happened last Monday night, between 9.30pm and 10pm.
A Northamptonshire Police spokesman said: “Police are appealing for witnesses following a robbery in Hunsbury Park near Dayrell Road, Northampton, on Monday, April 8, between 9.30pm and 10pm.
“The victim was attacked whilst he walked across the park and was pushed to the floor. He had cash and a Sony Experia mobile phone stolen from him.
“The offenders are described as five white men, all in their 20s.
“One of them was riding a silver BMX. Another was about 6ft tall, stocky, and wore grey tracksuit bottoms and a dark tracksuit top with the hood up.”