Some cannabis users think they are better drivers after taking the drug, according to a poll by the National Cannabis Prevention and Information Centre (NCPIC).

The NCPIC, based at the University of New South Wales, survey targeted 4,600 Australians over the age of 18 using social media.

It found nearly 70 per cent of recent cannabis users had driven while under the influence of the drug.

Sixteen per cent of users said they had driven on a daily basis less five hours after using.

Senior researcher at the NCPIC Dr Peter Gates said many users were oblivious to the impact cannabis had on driving skills.

"We hear a number of myths from cannabis users like that they may be more aware of their driving when they're stoned or that they're driving slower," he said.

Cannabis increases crash risk by up to 300 per cent: researcher

He said users' attitudes conflicted with established scientific evidence, showing cannabis increased the risk of motor vehicle crashes by up to 300 per cent.

"We know from research that any cannabis use will affect your tracking ability, your reaction time, your attention span, your awareness of distance, your co-ordination, concentration," Dr Gates said.

Dr Gates said users were also unaware of the risk of being drug tested, despite a rise in the number of random roadside drug tests being conducted.

"It is time for a wake-up call," he said.