Sir Bernard Hogan-Howe says that drug-testing would help cut the number of users - as the risk of losing your job would act as a deterrent.
"It seems to me we have got to plant in people’s minds something to affect the demand as well as supply. You can think of many occupations where if you were working with a colleague you would want to be sure in fact that they were drug free."
More top news
Two women had to be rushed to hospital after the driver of a 'BMW' mounted the pavement in a hit-and-run crash.
The shocking moment a cyclist was threatened by a driver with a metal baseball has been captured on a video posted online.
Music festivals and big sporting venues put on on “high alert” - one of Britain's most senior anti-terror police officers has revealed.