A police helicopter weighing less than a kilo will be trialled in Liverpool as part of an attempt to cut antisocial behaviour.

The Microdrone MD4-200 is under a metre long and can be equipped with a 10-megapixel camera, digital video or low-light and infrared units. 

The device can also be fitted with a GPS unit and sent on pre-programmed flights without a human operator.

"We are always looking at ways of putting more officers on the streets, and maximising technology is a powerful way of achieving this," said Simon Byrne, Assistant Chief Constable of Merseyside Police.

"The drone will support our Axis antisocial behaviour taskforce in gathering important evidence to put offenders before the courts.

"Other uses may include monitoring public disorder, crowd control during large scale events, and use during traffic congestion."

Merseyside Police is already using CCTV-equipped vans in Liverpool to gather evidence, and the new drones will be used in conjunction with these measures. The drones are already in use in Germany, Belgium and Norway.

Stephen Cahill, deputy director of the Police and Crime Standards Directorate, said: "We are pleased to support Merseyside Police in its efforts to reduce crime through the use of new technology. This trial is the first of its kind in the country and we are excited about its potential."

If the Liverpool trials are successful other forces are expected to use the technology across the country.