Herts Police are treating a series of masked robberies as linked after phones were taken.

The force has confirmed it is investigating three robberies and two attempted robberies which have been reported since the start of this month, in Cassiobury Park, Cassiobury Park Avenue, and Shepherds Road.

The statement followed nearby schools issuing safety advice, saying it was in response to a wave of robberies and violent assaults around Watford Underground Station and Cassiobury Park.

Inspector Dan Jones said: “I’d like to reassure members of the public that there have been no reports of weapons being used, however, we are treating them as linked.

“The incidents have involved groups of around four to five males wearing face coverings and demanding mobile phones.”

In an email to parents, Croxley Danes School asked them to discuss their children’s journeys to school and remind them not to engage in conversations with strangers and to be alert at all times.

It added that, where possible, pupils are encouraged to travel in pairs.

The Watford Neighbourhood Policing Team inspector said: “I appreciate this may cause concern amongst parents and guardians, as well as students, but I would like to reassure everyone that we have increased our patrols in the area, particularly around school times, to ensure children and young people feel safe when walking to and from school.

“We are working hard to identify those involved and encourage anyone with information to please come forward.

“We have also been liaising with relevant partner agencies including British Transport Police and local schools.”

He advised those walking around in public to keep all valuables secure and out of sight and asked anyone who witnesses a crime taking place to call 999 “straight away”, explaining that the force wants people to report suspicious behaviour or anything that does not look right if they are concerned.

“We would rather attend and find that everything is in order than miss an opportunity to potentially catch an offence in action,” the inspector added.

The email to parents claimed police had said there were "28 incidents in the area in the last 24 hours", referencing “robberies and violent assaults”.However, Herts Police have confirmed the figures are inaccurate and “categorically did not come from the police".