Police checked 13,532 cars and 16,731 drivers and passengers in one day during a crackdown on traffic law violations.
The checks targeted drink- and drug-driving, as well as people driving without a licence.
Officers caught 21 drivers behind the wheel after drinking. Tests showed 11 of them had between 0.5 and 1.2 per mille of alcohol in their blood, while 10 had more than 1.2. Two refused to take the test.
Five more drivers were caught driving under the influence of drugs or similar substances, and two of them refused to be tested.
Police issued 4,109 fines and drew up 480 reports for administrative offences.