Two Ashburton police officers have been cleared of planting evidence in a case that was dismissed by a judge.

The Independent Police Conduct Authority (IPCA) found that it was unlikely two Ashburton officers planted evidence by placing a man's wallet in a bag containing drugs.

However, the IPCA noted lapses in good practice made it difficult for the officers to corroborate their version of events.

Police searched a car and found a "bum bag" on its centre console which contained a small quantity of white crystals on May 15, 2017.

The bum bag was photographed in the car but the pictures did not clearly show whether the front seat passenger's wallet was also inside.

The passenger was taken to Ashburton Police Station, where he was searched and temporarily put into a cell.

The bum bag and its contents were set aside while both officers drove the arrested man to Dunsandel placing him in the custody of Christchurch-based officers.

Upon returning to Ashburton Police Station, one of the officers processed and photographed the exhibits.

He said he found the man's wallet in the bum bag, along with methamphetamine.

The man was charged with possessing methamphetamine.