A new multi-million-pound police helicopter will be able to give instructions to criminals and people on the ground over a giant tannoy.

The £4.6m Eurocopter, which will be based at RAF Benson and used by Thames Valley Police, is being built and will take to the skies in about 12 months' time.

The helicopter will track down suspects, monitor car chases and search for vulnerable or missing people.

Its high-tech kit includes a ‘SkyShout’ tannoy used to pass messages to the ground, and an ultra-powerful searchlight to pinpoint criminals and light up accident scenes.

Doug Mackay of Chiltern Air Support Unit, which runs the force helicopter, said: “The new aircraft will have the latest on-board equipment to further enhance the vital crime fighting and life-saving role performed by the existing helicopter.

“Aside from the humane aspect of assisting the public, often in times of extreme need or danger, the use of the police helicopter has long since been proven to be financially viable.

“Just one illustration of this is the aircraft can search an area which would take substantial ground resources days to accomplish, saving not only valuable time if a life is at risk, but also the large cost.”

The ‘Skyshout’ system can be used when searching for missing children in urban areas to ask members of the public to help in the search.

Crew can also yell at offenders from a distance.

The helicopter will also be used to transport patients to hospital at night because the air ambulance is not equipped to fly in hours of darkness.

The cost of the Eurocopter EC135 P2 helicopter rose over budget last year due to financial instability on the world markets – and Government cash is having to be used to help pay for it.

Last year, the force’s two helicopters attended 5,634 incidents, were involved on 868 arrests, helped recover more than £2m worth of stolen property and flew 39 people to hospital.

Policing Minister Vernon Coaker announced funding for the helicopter this week.

He said: “Air support units play a crucial role in helping police protect communities against crime.

The new helicopter will replace the Benson-based Eurocopter EC135T1.