Police officers in a marked police car in Landor Road, Stockwell indicated for a yellow and black Ford Transit tipper truck to stop at around 10.50am on the bank holiday.
Instead of stopping, the truck reversed at speed into the bonnet of a police car causing extensive damage.
One of the police officers was taken to hospital for injuries to his head and hand but he has since been discharged.
The second officer was assessed at the scene by paramedics.
It was a routine traffic stop because of the way the truck was being driven and damage to the vehicle.
The truck could not be located during a search of the area after the collision.
Police have launched an appeal to trace the tipper truck and identify those involved.
The truck is yellow and black in colour, with a damaged mirror on one side.
The registration is believed to be FA04 UZW, although the F is missing from the rear number plate.
Anyone who sees it is asked to call 999. Anyone with other information about those currently in control of it, or its recent whereabouts, should call 101, giving the reference 2376/15APR.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111.
