A teenager was hit over the head during a robbery at the junction of Hart Lane and Crawley Green Road.
The incident happened at about 6pm on December 28 when the 17-year-old was struck over the head from behind.
Two men demanded the victim’s phone before punching him in the face several times and searching his pockets - taking an LG mobile phone.
They left the scene on foot towards Park viaduct and the vicitim was left with brusing to his face.
The offenders are decribed as boys with an Asian appearance, around 16 years old.
One was carrying a black man bag across his chest.
Call Det Con David Elias in confidence on 01582 394376, or Bedfordshire Police on 101, or text information to 07786 200011.