Great white sharks have been spotted in the Far North, prompting a warning from the Houhora harbourmaster.

Northland Regional Council Houhora Harbourmaster Greg Gemmell has urged water users to be careful after the sharks had been spotted "rather hungry" in the Houhora Harbour.

"There have been half a dozen sightings over the last month," he said.

"Sightings have been inside Houhora Harbour as well as Henderson Bay and Rarawa Beach, so those are the areas people need to be wary of.

"We don't know if it's the same shark or not but it seems to be a small group of sharks.''

In a Facebook post alerting the Houhora community, Gemmell said the sharks appeared hungry.

"It has been bought to my attention from several locals that over recent times of late it appears we have a possible problem of our local waters having some large sharks that are rather hungry.

"These sharks have been sighted more than once by people that do know what a great white looks like.

"This has been both inside the harbour and up the coast on our local swimming beaches.

Gemmell told the Northern Advocate the great whites were estimated to be up to 4m in length.

"We're talking around 12-15 foot [3.6m to 4.2m] long sharks, which is quite big.

"There are a couple of smaller ones but it looks like there are a couple of larger ones too."

The Northern Advocate understood two great white sharks, ranging from two to two and a half metres long, were seen by a fisherman who were "burleying" to attract kingfish.

Gemmell said the warning has been issued as it was still warm enough to be swimming in Northland waters.

Signs were also being considered and Gemmell asked for any further sightings to be reported to him.