THEY usually come in yellow, blue or grey at the side of the road.

A flash from them and you know you've been clocked breaking the speed limit.

So just imagine a new breed of camera hidden away in no less than 19 message signs hanging from posts alongside one of the county's busiest stretches of motorway.

With not even a flash thousands of drivers who use the M27 between Hedge End and Portsmouth could be caught out 24 hours a day, 365 days a year. That's the rumour doing the rounds in a hoax e-mail spreading across Hampshire.

Headed 'M27 Speed Cameras' the anonymous author says the new signs designed to warn drivers of accidents and road conditions will be rigged up with speed cameras.

The so-called SPEC cameras work by recording registration numbers of cars as they pass underneath each of the hi-tech signs so a driver's average speed can be calculated. If a driver is found to be speeding an automatic speeding ticket will be sent out. The e-mail even says an unnamed transport minister came to switch on the cameras last Tuesday - a claim denied by the Department of Transport.

The overhead variable message signs are still under construction and will become operational next June.

Now the Highways Agency, Hampshire police and the Automobile Association are all working to quash the rumour.

Melese Glazer, Highways Agency spokeswoman said: "There is absolutely no question of speed cameras going up on any of the new signs. They are purely designed to warn drivers of what lies ahead, weather conditions and possible delays. We are trying to make our roads safer by making journey times more reliable and warning drivers if they have to find alternative routes.

"Variable message signs are one way of doing that."

A spokesman for Hampshire police Speed Camera Partnership said if speed cameras were to be installed, they would first publicise any plans.

He added that there are police control cameras along the M27 but these were designed to lookout for accidents and congestion.

A spokeswoman for the AA said: "The AA welcomes the use of these new electronic signs, especially in terms of driver information, but there are no truths to our knowledge in them being used to catch drivers for speeding."

All 19 motorway signs are due to become operational in June next year after work on the motorway's £10.5m upgrade began in February.