Seal breeding season is underway and an influx of kekeno pups and juveniles is expected on land as they began to wean from their mothers. (File photo)

A dog has attacked and killed a seal pup in Napier.

Dog attacks on seals are becoming more common, which was concerning, Department of Conservation Napier operations manager Connie Norgate said.

"Dog owners whose dogs attack seals are committing an offence, as the Dog Control Act requires them to keep their dogs under control at all times."

On Monday the dog's owner was walking the dog off lead on the beach, at West Shore in Napier.

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The dog was about 100 metres ahead of him when it came across the pup and attacked it.

The dog's owner ran to catch the dog to stop the attack, but it was too late to save the seal pup.

LUZ ZUNIGA Dog attacks on seals are becoming more common, which is concerning, DOC says. (File photo)

​Norgate said the breeding season is under way and an influx of kekeno pups and juveniles was expected on land as they began to wean from their mothers.

"Seals are protected under the Wildlife Act 1953 and owners of dogs that attack seals could face some hefty penalties.

"In this attack the dog owner did the responsible thing. He came forward and identified himself to DOC and we are thankful for that and are working with him to resolve the matter."

Seals were once hunted from the northern to the southern tips of New Zealand for their pelts, bringing them to the verge of extinction.

BRADEN FASTIER / STUFF Three Seals play off Rocks Road, in Nelson Harbour.

DOC takes a hands-off approach to kekeno because they are capable, resilient and if given time and space they usually find their way home. They are often just coming inshore to rest.

However, DOC rangers will intervene if the kekeno is in immediate danger, tangled in debris, causing disruption or being harassed by people or dogs.

It is an offence under the Marine Mammals Protection Act 1978 to disturb, harass, harm, injure or kill a seal. A dog owner whose dog attacks a seal can face prosecution.

People could help by ensuring dogs were under control and on a lead at all times.