A man ran from robbers who threatened him with a holstered knife and demanded he follow them after failing to hand over any money.
Although the 21-year-old had already given the two men his black iPhone 4, he was told to go with them when he showed an empty wallet - but managed to escape before doing so.
The victim had been walking from city centre along Redway towards Downsbarn when he saw the offenders walking towards him as he crossed the bridge onto Campbell Park on May 5 at 10.45pm.
One asked for the time and the victim responded, but continued to walk along with his mobile phone in his hand, while the other approached from the opposite direction.
The first offender was black, in his late teens to early twenties, about 5ft 11ins and of a stocky build.
He spoke with an English accent, had a round face and was wearing a grey hooded sweatshirt with the hood up and dark trousers or jeans.
The second offender was black, about 5ft 11ins tall, slimmer than the other male and was wearing a dark coat and dark jeans.
Anyone with information should contact Det Con Samantha Reynolds from Milton Keynes police station on the non-emergency number 101.
If you don’t want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org. No personal details are taken, information is not traced or recorded and you will not go to court.