A Department of Conservation marine scientist is warning a shark seen in the inner Waitemata Harbour in Auckland is a great white.

The shark was seen by a family fishing in the upper harbour on Monday.

Marine scientist Clinton Duffy says the shark, thought to be about four metres long, is a great white that's probably come into the area to feed.

He says it's not unusual, but people fishing, kayaking or kite surfing in that part of the Waitemata should be careful - and dead fish or old bait shouldn't be dumped into the water - as it will attract the shark.

There have been no further sightings of this great white reported to DOC.