Police want to speak to two possible witnesses after a teenage girl was sexually assaulted on Hampstead Heath.

The 15-year-old was sexually assaulted by a male near the Parliament Hill Viewpoint at around 10.45pm on Saturday (June 3).

In response to an earlier appeal, detectives now believe that the suspect – who is described as aged in his late teens, around 5ft 8ins tall, with short brown hair - was wearing a black zipped top and black tracksuit trousers.

Detectives have also identified two possible eye witnesses they would like to speak to.

The first is described as a white male with spiky short light brown or blond hair, wearing a grey coat with a furry hood and tight grey cargo trousers.

The second is a white male with black hair in a ‘curtains’ style, wearing skinny washed out blue jeans and a white T-shirt.

Detective Sergeant Sam Lockstone, from the local policing team in Camden, said: "We have carried out a number of enquiries, including a trawl for CCTV and a forensic examination of the scene.

"We believe there were a large number of teenagers on Parliament Hill at the time of the assault and it is thought the victim and suspect were part of different friendship groups.

"I am asking for anyone who witnessed suspicious activity, or has information about the incident, to contact us immediately.

"I would also encourage parents of children who were in the area that night to ask them if they can assist the investigation."

Anyone with information should call 101 quoting CAD 7852/3Jun.

People can also direct message@MetCC on Twitter.

Alternatively contact Crimestoppers anonymously on 0800 555 111