GRAFFITI vandals have exposed the location of one of Victoria Police's secret speed traps. 

The Herald Sun this week revealed camouflaged cops were hiding in thick bush to nab speeding motorists in the Yarra Ranges and elsewhere.

A person armed with a spray can has painted a pig's head next to the word "cops" and an arrow pointing to the exact spot where police hide with their radar guns on the Black Spur section of the Maroondah Highway.

Pigs' heads and large dollar signs have also been sprayed as warning signs on both sides of the road just before the concealed speed trap.

Almost 1000 motorists have already been booked at the site and police have vowed to continue using the undercover tactic.

Victoria Police acting superintendent Michael West yesterday said the criminal damage at the Yarra Ranges site was disappointing as the camouflaged cop tactic was being used to help save lives.

"Since the operation was introduced in the Yarra Ranges, injury collisions involving motorcycles have dropped by 38 per cent," he said.

"Victoria Police makes no apologies for using innovative tactics to try and change road user behaviour and reduce road trauma."

Recently retired detective Sen-Sgt Neil Beeson said he, and many other serving and retired officers, were disappointed police had stooped to using such "sneaky tactics".

The 38-year police veteran said the force had to have the public onside if it was to work effectively.

Read more at The Herald Sun