New police speed indicator devices flash motorists a smile when they drive within the speed limit but frowns when they drive too fast.

The device also shows drivers' speeds as they approach in a bid to embarrass them into slowing down.

The new mobile equipment was launched across Sussex today and will be used near accident blackspots, schools and where speeding vehicles pose a threat to pedestrians.

It is an alternative system to speed cameras and drivers caught speeding by the device will not be fined.

By next week there will be seven devices, bought at a cost of £3,200 each by Sussex Safety Camera Partnership out of money raised by speeding fines.

They will be manned by operators employed by the partnership which is made up of Sussex Police, Brighton and Hove City Council, East Sussex County Council, West Sussex County Council, Sussex magistrates courts and the Highways Agency.

The partnership was launched in October last year with the aim of preventing more deaths and injuries on the roads.

This year, 87 people have been killed on Sussex roads.

The partnership's aim is to reduce the number of people killed and seriously injured at fixed camera sites by 40 per cent during the next three years.

Superintendent Nick Wilkinson, head of Sussex Police road policing department, said: "We have got to use a wide range of methods to influence driver behaviour. Safety cameras are not the only answer. "

The partnership said the devices should not distract drivers.

Spokeswoman Emma Rogers said: "Drivers should be aware of everything going on around them. It should be a warning and part of your driving experience."

Similar devices called vehicle activated signs are in fixed locations, including the A24 and Nevill Road, Hove.

Mike Jee, headteacher of nearby Aldrington Primary School, said: "The flashing sign does make you check your speed. It is effective."

Neil Hunter, headteacher of Blatchington Mill School, agreed motorists were driving more slowly.

But residents in Nevill Road said signs had not stopped drivers speeding.

Sally Pead, who has two 16-year-children and an 11-year-old, said: "All they do is flash if you are going too fast and people ignore them."

Her nextdoor neighbour, Wally Gray, said: "If they want it to slow people down, it needs to be a camera."

Raymond Brooks said: "The whole arrangement was a waste of money. I do not think it has made any difference to the traffic flow."

Residents who would like their road or area to be considered as a site for a device should call 01273 482289.