Police are warning people not to consume any food found on the street or left in letterboxes after chocolates containing a potentially hazardous substance were found in Perth’s south over the weekend.

Chocolates like this have been found in Fremantle containing unknown substances.

Several wrapped mini-chocolates were found in Fremantle on Saturday containing an “unknown substance”, which police forensics were now investigating.

A local resident said the chocolates were found near the corner of High and East streets and had been left in areas accessible to small children and pets.

The resident, who wished to remain anonymous, said police knocked on her door on Saturday night and had been warning people in the area of their find.