A teenager was robbed of his mobile phone by a knife-wielding cyclist in Fishermead on Wednesday evening.
The victim was walking on the bridge over V7 from Oldbrook when he was approached by a man riding a black BMX bike.
When the man asked the boy for the time he took out his mobile phone which was then snatched from his hand. The victim attempted to stop the man from getting away, at which point the man showed him a knife before cycling away towards Jubilee Wood School.
The offender was black, in his late twenties or early thirties, and of normal to slim build, wearing a sandy coloured hooded top with a checkered pattern and blue jeans.
The mobile phone was a white Samsung Galaxy Note in a black case with a tiger design on it.
If you have any information which could help with the investigation, contact Milton Keynes CID on 101.
Alternatively call Crimestoppers on 0800 555 111.