A girl of 13 is thought to be on the run with a man she met through an internet chatroom.

Police have been tracking Samantha Boswood's movements each time she uses her mobile phone.

However, she appears to be trying to avoid contact.

Sergeant Karen Pirrie, of Brighton police, said: "She knows we are trying to locate her and we have left a message on her phone.

"It appears she is trying to cover her tracks.

"We know she is using an alias, Lizzie or Victoria Stark. She is only 13 but she can look a lot older. She is a bit of a loner.

"Samantha has had no problems at her Brighton home but we know she uses internet chatrooms.

"One of our lines of inquiries is that she may have met someone through a chatroom.

"We, her parents and her younger sister are worried for her safety.

"If you see this appeal, Samantha, please get in touch to let us know you are safe."

Samantha left home at 8.10am on Wednesday to attend Varndean School in Brighton.

At 11.05am she spoke to her mother on her mobile phone and said she was in Highams Park in London.

She was last traced, via her mobile phone, to Chatham in Kent last night.

Sgt Pirrie said: "Samantha, you are not in trouble. Your mother is extremely worried and needs to know you are okay.

"If you have no money, or if your mobile phone battery has run out, please go to a nearby police station and get them to call us."

Samantha is white with very long straight blonde hair and green-blue eyes.

She is 5ft, medium build and was wearing a white crew-neck T-shirt, black trousers, a black hooded fleece jacket and trainers.

Sgt Pirrie said: "If anyone has seen Samantha, or knows where she is, please get in touch with the police as soon as possible."

Anyone with information about Samantha can call Sussex Police on 0845 6070999.