Police are seeking any witnesses or dashcam footage of a dangerous driver at Morphett Vale yesterday afternoon.

The red Mazda 2 sedan was allegedly being driven erratically and at speed through the intersection of Main South Road and Flaxmill Road about 5.15pm on Friday 9 April, nearly crashing into the median strip.

Police followed the vehicle and noticed a toddler sitting unrestrained on the front passenger's lap.

The vehicle was stopped and the driver, a 32-year-old Morphett Vale man, recorded a blood alcohol reading of 0.120, more than twice the legal limit.  He also tested positive to methamphetamine and cannabis.

He was reported for aggravated driving without due care, drink driving and having an unrestrained child in the vehicle.  He received a drug diversion for a small quantity of what is suspected of being methamphetamine.

He was issued with a six month instant loss of licence and his car was impounded for 28 days.  He will be summonsed to appear in court at a later date.

Police are keen to speak with anyone who witnessed this man's manner of driving, or captured it on dashcam.  Anyone with information is asked to contact Crime Stoppers on 1800 333 000 or online at www.crimestopperssa.com.au

The Department for Child Protection was notified of the incident.