Police have stepped up patrols around the spot where a teenager was indecently assaulted by a man with a knife.

The 13-year-old was attacked at playing fields in Avenue de Chartres, Chichester, as she walked home from school.

She was pushed to the ground on a footpath behind the park.

The attacker pinned her down, showed her a knife and then assaulted her.

A police spokeswoman said: "While this was happening, two young males were walking along the same path and probably disturbed the attack.

"The male ran off towards the footbridge where a woman was walking."

Police have asked for witnesses to the attack, at 3.30pm on January 8, to come forward.

The attacker was described as white, slim, aged in his 20s and wore dark blue jeans and a black or blue hooded Reebok top.

He smokes cigarettes and had a local accent.