The Metropolitan Police force paid out £13m in compensation for traffic accidents involving its officers in the past five years, it has been revealed.
The Met paid £2m in compensation for traffic accidents in 2006
Figures obtained by the London Assembly Green Party showed that police lost about 26,500 work days as a result.
Green Party member Jenny Jones said: "This is a huge waste of money. There are no excuses for driving too fast."
A Met spokesman said the amount paid in compensation had fallen despite an increase in the number of claims.
The amount paid out in compensation by the Met fell from £3.4m in 2002 to £1.9m last year.
The amount paid covered damage or personal injury caused as a result of a collision with a police vehicle when Metropolitan Police had been at fault.
The assembly's Conservative policing spokesman Richard Barnes described the overall compensation figure as "staggeringly high".
"Is this a case of continuous incompetence, or have the ambulance chasers found a new cow to milk?" he said.
"London taxpayers are entitled to know why the Met has had to pay out this much. This money could have been spent on putting roughly 400 new officers on London's streets."
A Metropolitan Police spokesman said its 5,000 vehicles travelled about 62 million miles while policing the capital last year.
"Accidents should be seen in the context of the number of our vehicles on the roads and the challenging driving environment where officers respond to 999 calls or are in pursuit of suspects," he said.
He added that the Met "takes a robust approach to defending actions through its new dedicated claims team for road accidents".
A total of 6,525 claims were made against the Met following such accidents in the past five years, with 1,140 claims in 2002 rising to 1,529 claims last year.
The Met spokesman denied the charge of "incompetence" and said officers must complete specialist training in order to become police drivers.
He said the amount paid in compensation came from a Met budget covering such accidents, therefore it did not affect the number of officers on London streets.
However Green Party member Jenny Jones said: "If you lose a robber because you refuse to drive too fast, but you also do not kill or injure somebody in the process, then I think that is a worthwhile trade."