A little blue penguin swims in rapids on the Avon River outside the the earthquake memorial site near the Montreal St bridge on Christchurch's Oxford Tce.

A little blue penguin has been spotted in the Avon River in central Christchurch.

Contractors working on the Canterbury Earthquake National Memorial on Oxford Tce reported seeing the sea bird, which soon drew a crowd of would-be penguin spotters.

Department of Conservation (DOC) ranger Jenna Thoms said there was no cause for concern.

JOSEPH JOHNSON/FAIRFAX NZ The penguin went from the surf, to surfing the rapids on the Avon River in central Christchurch.

"I went down there today after we had a few phone calls and I found him in the centre of town. He seems quite happy and healthy.

"[He's] just swimming up and down some rapids, doing some fishing. So, at this stage, we're just going to leave him alone."

Thoms said the public should give the penguin space and keep dogs on a leash.

JOSEPH JOHNSON/FAIRFAX NZ The little blue penguin swimming in the Avon River.

"Dogs can jump into the river quite easily and maul it (the penguin) in seconds."

She said it was "slightly unusual", but not unheard-of, to see a penguin so far up the river.

The river flows into the Avon Heathcote Estuary, several kilometres away.

JOSEPH JOHNSON/FAIRFAX NZ Little blue penguins are commonly seen along New Zealand's coast.

Little blue penguins, or korora, are the world's smallest penguins and commonly seen around the New Zealand coastline.

If anyone has any concerns about the wellbeing of the penguin, they should call DOC on 0800 362 468.