Teenager are holding “rowdy” all-night parties while illegally camping on land within a national park.

Youngsters have been seen walking up Southwick Hill in Portslade with camping gear on Friday evenings for a weekend of celebration.

Residents have reported hearing music into the early hours with dozens of abandoned cans and bottles littered across the countryside.

Police and National Trust officers are now conducting searches of the area to track down the culprits.

Reports of the late-night parties were first made a couple of weeks ago.

However, neighbours have said the music gets louder and rubbish increases every weekend.

A National Trust spokeswoman confirmed it was aware of the situation and had been in touch with police.

Teams are now clearing the area of rubbish while officers from both bodies are also conducting patrols to track down those responsible.

The land, which falls within the South Downs National Park, belongs to the National Trust.

It should be designated as public land but a by-law makes camping illegal in the area.A spokeswoman for South Downs National Park authority said it would work with the landowner to ensure it could limit the damage.