Police are investigating after it was reported a man approached two girls on Wimpson Lane on Tuesday 14 December and sexually assaulted one of them.
The incident happened at 7.30am when the girls were walking to school together.
The girl who was assaulted, who is 12-years-old, is being supported by specialist officers.
Her friend, a 13-year-old girl who was with her at the time, acted quickly and called the police.
Police deployed to the area immediately and carried out thorough area search to try and locate the offender.
Officers also then sent out teams to carry out house to house enquiries in the area and scope CCTV opportunities.
Police have also alerted schools in the area about the incident.
The man has been described as white with a stocky build and below average height, wearing an orange hi-vis jacket, dark blue working men’s trousers and working boots.
Detective Sergeant Jamie Wiseman said: “This is very worrying incident and our absolutely priority is to identify this man.
“Whilst we have increased patrols in the area and are carrying out enquiries, we want to ask anyone who was in Wimpson Lane yesterday morning around this time who saw a man matching this description, to get in contact with us.
“We know that the man was on foot, walking from Romsey Road into Wimpson Lane and he walked back from Wimpson Lane into Romsey Road. This was between 7.20am and 7.40am.
“We are specifically keen to hear from anyone who was driving along Wimpson Lane at this time with dash cam footage to come forward, you may have captured valuable footage that will help us identify this man.
“Anyone with information must contact us as soon as possible. This is a priority for us.
“Please call 101 and quote 44210499863.”
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