A drug driver was caught twice in two hours last night.

About 11pm Friday 7 July police were conducting speed detection duties on the Southern Expressway when they detected a Honda sedan travelling at 149km/h in the 100km/h zone.

Police activated their emergency lights and were able to stop the car as it turned onto Main South Road at Noarlunga Downs. Police spoke to the driver, a 20-year-old Enfield man, and submitted him to a drug test. He allegedly returned a positive result to driving with cannabis in his system.

Checks revealed the man had been stopped by other police approximately two hours earlier on South Road at Croydon Park where he had failed a drug test and was issued a direction not to drive for 24 hours.

He was reported for speeding, breach of P licence and lost his licence on the spot for six months. His car was towed from the scene and impounded for 28 days. He will be summonsed to appear before the Christies Beach Magistrates Court at a later date.

Police located a small amount of cannabis inside the vehicle which was seized and the man issued a cannabis expiation notice totalling $499.

His drug driving sample will be sent to Forensic Science SA for further analysis.