The popular Orewa Beach in northern Auckland is closed to swimmers after multiple sightings of a large shark.

Photo: Rafael Ben-Ari / 123RF

Surf Life Saving Northern Region duty officer Dan Short said the beach was closed for a few hours yesterday after reports of a 2m shark swimming about 500m offshore.

Today, lifeguards received multiple reports from paddleboarders who say they saw a shark of a similar size between 150m and 500m offshore.

About 500 people are recorded as being at the beach today and lifeguards are proactively warning people not to swim at the moment.

"If it's coming in close to the shore, close to where we've put our designated swimming area, it's generally where we'll close the flags more as a precaution," Short said.

"The sightings yesterday and today in particular, [the shark] hasn't been showing any dangerous activity, it hasn't been breaching, or feeding, or thrashing or anything like that. It's just been noticed with its fin coming out of the water as it's swimming around."

Swimming is also not advised at nearby Hatfields Beach and Red Beach.