Up to eight people are feared dead after a chartered fishing boat sank in New Zealand, police said.

Five bodies have been recovered and three people remain missing seven hours after the vessel overturned near Kaipara Harbour, north of Auckland.

The police initially said six people had been pulled from the water but later confirmed only three survivors had been found.

"The bodies of five people have been recovered from Kaipara Harbour," the police said in a statement.

"Three other people have been rescued and are in hospital. A search for a further three people will continue."

Police have been told that 11 people were on the boat, known as The Francie, which went down when returning to the harbour in the afternoon.

The Francie, listed as a 12-metre (40-foot) long boat that can carry a maximum of 22 people, capsized at the entrance to Kaipara Harbour.

Police inspector Duncan Hall told reporters a shoreline search would continue during the night for the missing three people but an aerial search had been called off.

"Conditions are not suitable for an air search to continue tonight due to a significant sea swell. Visibility is poor, which would put rescue aircraft and their crews at risk," he said.

A former skipper of The Francie, who now operates another charter boat, told the New Zealand Herald that conditions were "too rough" to have taken the vessel out of the harbour.

"I stayed home...the wind was coming up and the swell was coming up. You wouldn't go out over the bar," the Herald quoted him saying.