There has been a steady increase in the number of motorists convicted of driving under the influence of drugs since new saliva tests were introduced in 2017, news website Nu.nl said on Monday.

In 2017, 1,834 people were caught driving after taking drugs, but by last year that had risen to 13,000, the police figures show.

By contrast, drink driving offences have gone down for the past couple of years, with 17,500 people convicted for driving while drunk last year.

Prior to 2017, driving under the influence of drugs was not a separate offence. Instead, motorists were convicted of dangerous driving, and drug use was a factor in sentencing.

The records do not state what sort of drug drivers had been taking but other police figures show laughing gas had a role in 1,800 traffic accidents in the past three years, including 63 that were fatal.