Authorities are investigating a report of a crocodile sighting in Brisbane's north this afternoon.

The Environment Department says a fisherman reported seeing a three-metre crocodile swimming in Schultz Canal, before heading up Jacksons Creek near Nudgee Beach.

Wildlife officers searched the area and found no sign of a crocodile, but have put up signs as a precaution.

Crocs are not known to inhabit Queensland's south-east.

The department says there has been no confirmed sighting of a crocodile in the wild south of Gladstone in the past 100 years.