The 19-year-old was sitting with friends on a bench in Railway Street, Chatham, Kent, when they were approached by two men and a woman.

The group were said to have been abusive, and then the woman "struck the victim in the stomach".

She attended hospital where staff found "two small wounds that were consistent with needle punctures", police said.

CCTV examined

The incident happened between 0045 BST and 0115 BST on Saturday.

Det Con Dave Cooper said: "'This has caused a great deal of distress and anxiety to the woman involved and we are keen to arrest the person responsible."

He said CCTV footage of the area was being examined.

The woman who carried out the assault was described as white, about 5ft 2in tall, with blonde shoulder-length hair, dark eyes, and a round face with a pointed jaw.

She was wearing cream or yellow-coloured clothing.

One of the two men with her was described as white, aged either 16 or 17, and with dark hair.