The juvenile freshwater crocodile was first spotted by a group of teenagers in Ironbark Creek in the Australian city on Saturday

An Australian freshwater crocodile has been captured in a city creek thousands of kilometres south of its normal range, after sightings shocked onlookers at a suburban park.

The crocodile was first spotted in Ironbark Creek in Newcastle – about 100km north of Sydney – around midday on Saturday, by a group of teenagers.

Stephanie Kirsop, a mother of one of the teenagers, said when her son called her to relay the sighting, her initial reaction was: “This is a trick … it looks like a crocodile but that’s probably a log.”

“It took him about two hours to fully convince me to go down there and have a look,” she said. “I get there, I look and here’s this little crocodile swimming around in the water.”