Owen Sound police are desperately trying to locate some methadone, after a backpack was taken at a local eatery.

Police warn even a small dose of methodone can be dangerous to children and a larger does can also harm adults.

The warning comes after a man mistakenly left his backpack containing the prescription methadone at an restaurant on 9th Street East around 9 a.m. Monday.

The backpack was camouflage and inside was a locked black case containing six 200 millilitre bottles of methadone.

The man contacted police on Wednesday after attempts to locate the backpack failed.

The bottles each have about a juice box amount of methadone and child-proof lids.

Anyone with information is asked to contact the investigating officer, Const, Houston at 519-376-1234 ext 177.