SA trucks found with serious defects

Almost 600 heavy vehicles on South Australian roads over the past month were defective, including 80 with serious brake problems.

Police checked more than 4000 trucks and other heavy vehicles during Operation AUSTRANS, identifying 559 with defects and 158 with major issues.

There were also a number of incidents where drivers were grounded for either exceeding their working hours or failing to take minimum rest time.

"The risk to the drivers and to other road users speaks for itself ... drivers or operators who are involved in risk-taking behaviour will be targeted by police, state-wide," inspector Ben Spencer said on Wednesday.

"A fatigued driver operating a heavy vehicle creates an extreme and unacceptable risk."

Truck safety has become a major focus for police after several fatal incidents in which drivers lost control of their vehicles on Adelaide's South Eastern Freeway.

Dozens of truck drivers were also caught using a mobile phone while driving or not using a seatbelt.