A device used to stop anti-social behaviour among young people in Hertsmere has been at the centre of a national controversy this week.

The Mosquito alarm emits a high-pitched ultrasonic noise which can only be heard by people under the age of 25.

It was first piloted in Borehamwood and Radlett in 2006 with the aim of combating youths gathering in large groups and causing problems for shops and residents. But a new campaign called Buzz Off, led by Sir Al Aynsley-Green, the children's commissioner for England, and backed by organisations including civil liberties group Liberty, is calling for the device to be banned. Sir Al said: "These devices are indiscriminate and target all children and young people, including babies, regardless of whether they are behaving or misbehaving. "The use of measures such as these are simply demonising children, creating a dangerous and widening divide between the young and the old. This has to end now."Shami Chakrabarti, director of Liberty, said: "What type of society uses a low-level sonic weapon on its children? "Imagine the outcry if a device was introduced that caused blanket discomfort to people of one race or gender, rather than to our kids." But Chrissy Barclay, Hertsmere's crime prevention officer, still believes the alarms, which cost around £500, can be affective in combating anti-social behaviour. She said: "Hertsmere has been very cautious about implementing the mosquito alarm. But it is another tool in our tool kit. "Young people have to learn that certain behaviours are not acceptable, like standing in groups and being intimidating, or gathering outside shops and off-licences."Although the Hertsmere Crime and Disorder Reduction Partnership (CDRP) has the power to fund an alarm, it has not yet done so. Currently shopkeepers and residents can buy their own alarm to place outside their property.

Councillor John Donne, chairman of the CDRP, said: "I have no problem with the alarms. I can see the benefits of them and how well they clear places which have problems.

"Anything that is effective can't be all bad and it only discriminates against those that are causing the problems."