A total of 306 motorists failed drink-drive breath tests and 131 others tested positive for drugs during a summer clampdown, report police.
In 2015, 52 drivers tested positive for drugs after new laws were introduced.
More than 9,500 breath tests and 190 drug wipes were administered during the All Wales Campaign in June and July.
The latest national figures from the police show worrying signs, with a large drop in the amount of people being tested but an increase in those who tested positive, failed or refusing the test, said Gary Rae, director of communications and campaigns for Brake, the road safety charity.
Calling on the Government to invest more in traffic policing, he added, “With traffic police numbers on the decline, it’s leaving those who enforce the law with very little resources to catch those who do break the law and despite the police claims of a successful targeted strategy, the degree to which this is actually the case is impossible to know.”
