The sight of birthday greetings and personal messages on sheets and banners attached to roadside signs and railings has been condemned as a potential traffic hazard.

Police and county council officers have joined forces to criticise the over-used practice, which they fear could distract drivers and cause a collision.

They spoke out as an impromtu marriage proposal appeared on the Kidlington roundabout, near Sainsbury's supermarket.

The message read: "Matt Williams, U Sex Pest! Will U Marry Me? Love Amy xxx"

Often the homemade displays are not removed after the event and are left to deteriorate unless they are spotted and taken down by highways engineers.

Geoff Barrell, principal highways officer for Oxfordshire County Council, said of the public marriage plea in Kidlington: "It's an unauthorised sign as far as we are concerned, and we don't approve of them.

"They are a distraction to motorists as they are often put on top of warning signs. It's not something we approve of and our maintenance people do remove them when they come across them."

A spokesman for Thames Valley Police said: "Although these messages are not strictly speaking a criminal offence, they can be hazardous to motorists by obstructing road signs and causing a distraction to drivers.

"Thames Valley Police would advise the public not to engage in activity which could cause a collision".

Michael Badcock, the recently elected Tory county councillor for Abingdon West division, said that a roundabout in Drayton Road was often the focus for impromptu messages.

He said: "It could be seen as a form a graffiti, but I suppose it's a matter of taste. Providing it's not causing harm or a traffic hazard, I don't see there's a real problem -- but I do think people should remove them afterwards."