The number of people charged with driving with illicit drugs in their system in NSW has risen 300 per cent following a concerted state government crackdown, according to a report from the state's crime statisticians.

About 9800 people had charges for driving under the influence of drugs finalised in local courts last financial year, compared with 2300 the year prior, according to Bureau of Crime Statistics and Research analysis of court data released on Tuesday. That amounts to a rise of some 320 per cent.

Drivers are swabbed but only for certain classes of drugs.

"It seems likely that the increase in charges is a reflection of increased law enforcement activity rather than an increase in actual drug driving," the report concludes.

That follows a pledge in 2015 by Police Minister Troy Grant to triple the number of roadside drug tests conducted each year to 100,0000.