'No excuse' for SA drivers under influence

The number of drivers caught under the influence of alcohol or drugs with schoolchildren in the car has shocked South Australian police.

A police road blitz on Friday caught nine drivers with drugs or alcohol in their system while children were in the car or had just been dropped off at school, police say.

"I am shocked that so many parents would put both their children and other people in danger while driving under the influence," said Superintendent Anthony Fioravanti.

"There is no excuse for this and the law could not be any clearer."

Operation Stop Drink-Drug Drive ran 286 drug screening tests and 1219 alcohol tests on Friday, which showed that 17 drivers returned positive drug tests while four motorists tested positive for alcohol.