Police have stepped up patrols on Hampstead Heath after three knife robberies over the bank holiday weekend.

The attacks, near the Lido swimming pool by the Gospel Oak entrance to Parliament Hill, took place between 9pm and 10pm on Friday and Saturday evenings.

PC John Hounsell, from Highgate neighbourhood policing team, said: “All victims have been males in their mid to late teens, and a knife has been used to threaten victims on every occasion.”

He said officers from Highgate’s safer neighbourhood team were working with with the Hampstead Heath Constabulary to step up night patrols in the area over the next two weeks.

Detective are currently investigating the offences.

PC Hounsell warned people using the Heath at night to stick to well-lit areas or seek alternative routes such as via roads or public transport to cross the Heath.

He said: “Try to avoid dimly lit areas. The Lido on Parliament Hill is a very dark area and we would advise avoiding this during darkness hours. Avoid travelling alone on the Heath.

The attacks come weeks after another teenager was injured in an attack by a group of youths at around 6:30pm on Sunday May 8.