Two teenage youths have stolen a schoolboy's mobile phone, trainers and jacket after one of them sat on his chest while he was on his way to school.

Officers now want the public's help in tracing the youths, one of whom pushed the victim to the ground where he injured his forehead.

The youths took the boy's Nike 'Air-Max' trainers when he was on the floor and then his black Ecco coat - with a Rhino image on the front and containing his white Sony Ericsson W850I mobile phone - after he stood up.

The boy was robbed at approximately 8.30am on Thursday, February 7 in an alley off Chelmsford Drive, running towards Nunnery Wood School, when the victim was walking to school with a friend - who was some way off when the incident occurred.

Both youths, who are believed to be white, wore dark clothing - black tops with the hoods up, possibly with peaked hoods or caps and black trousers.

The first is described as approximately 16-17 years old, around 5ft 7ins tall, of medium build with broad shoulders. The second was around 19-20 years old, slightly shorter than the first and of chubby build. They both wore black gloves - one pair possibly being mesh-type, red-flecked Nike cycling gloves.

Anyone who saw what happened, the youths acting suspiciously before or afterwards - or who recognises their descriptions - can contact police on 08457 444 888, quoting 155S/070208.