A national operation targeting the use of mobile phones while driving is being mounted by gardaí today and tomorrow.
There had been almost 300 detections for holding a mobile phone while driving by lunchtime today.
In a statement, gardaí said mobile phone use by drivers remained a significant issue.
Almost 10,000 motorists were detected holding a device in the first three months of this year.
Gardaí said research showed there is a four-fold increase in the risk of having a crash when using a phone.