Thousands of motorists were caught drink- or drug-driving in a month during a summer police blitz, figures show.
Almost 50,000 vehicles were stopped between June 10 and July 10, with 45,000 breath tests carried out.
The National Police Chiefs’ Council (NPCC) launched a campaign to target those who drive under the influence in June. The figures cover Northern Ireland, England and Wales.
Of those, 4,539, or a tenth, were found to be positive, refused - meaning the driver would not give a specimen of breath - or failed - meaning a specimen is given, but it is not sufficient to determine a result.
Meanwhile, drug screening devices were deployed on 2,588 occasions, with 1,028 positive tests.
Police can also make those they stop carry out a “field impairment assessment” if they suspect them to have taken drugs. Some 279 of these tests were carried out over the month, with 80 resulting in an arrest.
Under new legislation legal driving limits were laid down for 17 prescription and illegal drugs in March last year.
There is virtually zero tolerance for drivers apprehended with substances such as heroin, cocaine and cannabis in their system.
Fewer cars were stopped and tests carried out compared to the initiative last summer, but a larger proportion of alcohol tests were positive, refused or failed.
Chief Constable Suzette Davenport, national lead for roads policing, said: “It is encouraging to see that our intelligence-led approach continues to work - fewer tests administered but increased criminal justice outcomes, with forces actively targeting hotspots and using their local knowledge to get drink- and drug-drivers off our roads.
“Even though this has been a successful summer campaign, it is still disappointing to see during the campaign over 4,500 people drink driving and over 1,000 people driving whilst under the influence of drugs.
“We remind those who drive when intoxicated that police forces across the country are better equipped than ever before to detect and prosecute drivers who ignore the law.”
She added: “We continue to see the benefit of the new drug-driving law and swab kits with nearly 40% of those being screened testing positive at the road-side and being prevented from causing harm to other road users.”
Gary Rae, of road safety charity Brake, said: “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.”