The police say that a staged accident is the culmination of the preparation of a criminal act. As such the vehicles now form a crime scene. It is unlikely a commercial vehicle driver will persuade a team of detectives to attend - many forces now only attend personal injury accidents. Therefore it is possible that even a request for uniform police help will be declined.

The police say that common sense rules apply. While the driver who has been targetted may be in shock, it will generally be true that he/she will not be dealing with a major incident. The "victims" do not want the emergency services to attend.

A summary of what to do follows:

• Keep a safe distance from the protagonists and stay calm. Under no circumstances become aggressive. Exchange details, make a note of damage, the driver's description, plus the number of people in the car
• Carry a disposable camera so you can photograph any damage, the immediate scene and road markings. The police say that if the "victims" happen to get into these shots it can be useful, but do not overtly photograph them.
• Look for independent witnesses. Do not accept anyone who puts themselves forward too eagerly. They could be involved in the scam.
• If you suspect anyone is hurt offer to call police and ambulance. Note the responses.
• Any notes taken at the scene should be signed, dated and stored securely with a copy of the tachograph or digital printout and any images. Call your insurer as soon as possible.

Police add that if a driver is forced to take evasive action to avoid another vehicle, and an accident is claimed by a third vehicle's occupants, if the original vehicle fails to stop it is an offence. A description or vehicle registration number of the 'nostop' vehicle will help police. Police say offenders have a limited fleet to use in these crimes.

There is a confidential insurance cheat line. The number is: 0800 328 2550.