A Gisborne boy has been attacked by a large seal at Mahia, suffering puncture wounds to his arm.

The 10-year-old was walking through grass late this morning, on his way to fish at Snapper Rock on the eastern side of Mahia Peninsula, when the seal suddenly lunged at him.

Nuhaka Police Constable Craig Henneker says it appears the boy startled the seal - his mother says he didn't know the animal was there.

The seal, believed to be an adult fur or leopard seal, disappeared into the sea after the attack.

DOC staff from Wairoa were called and have been checking to see whether the seal has come ashore again.

The boy's wounds were treated in hospital this afternoon.