Police are appealing for witnesses after two teenage males were robbed by two males on a moped in an alleyway off Lancaster Way, Worcester Park, on Monday, 21 November at 21:30hrs.
The teenagers, who were on foot, were stopped by the suspects and threatened with a knife.
The suspects were wearing masks and crash helmets. They stole a mobile phone and cash before making off on a red moped.
If you have any information, contact Sutton Police Station on 101. Alternatively, contact Crimestoppers anonymously on 0800 555 111.