'Where was the tranquiliser?': Outrage after security dog shot dead at Auckland Airport

New Zealanders have expressed their outrage after an aviation security dog was shot dead today after getting loose at Auckland Airport, causing delays to flights.

An Auckland Airport spokeswoman said staff spent more than three hours trying to catch the dog named Grizz.

"Unfortunately as a last resort they had to shoot him," she said.

About 16 domestic and international flights were delayed after the dog broke free into the airfield at about 4.30am on Friday.

Auckland Airport took to Twitter to warn passengers that they were facing flight delays "due to a dog on our airfield".

Flights had resumed by 8am but there was a backlog, she said.

The airport later tweeted its thoughts were with the dog's handler.

Police Inspector Tracy Phillips said officers had been directed by airport staff to shoot the dog.

"This is not an outcome which anyone wanted, and police were only asked to be involved as a last resort," he said.

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Police said the shooting followed considerable efforts over several hours by AVSEC and airport staff to contain the dog after it was first reported to be loose at 4am.

"Our thoughts are with the AVSEC dog handler involved," he said.

TVNZ Breakfast host Hilary Barry spoke out on air against the decision to shoot the dog.

"It's only Auckland Airport. Sixteen flights were delayed, so. So they shot it! They shot it dead.

"Where was the tranquiliser?" Barry demanded, adding, "They have got to have tranquilisers there."

Author Juliette Banks‏ shared her outrage on Twitter.

"Embarrassed to be a kiwi today. Killing a dog so flights can continue Auckland Airport. No excuse! Disgusting," she posted.

Several others took to Twitter to question why the dog had to be shot dead.

Comment has been requested from Aviation Security.

Explosive detector dogs are employed at airports to sniff out bombs, rather than drugs. Each dog is paired with a handler.

Some passengers took to Twitter to report the incident.

The Airport said the dog was caught just before 7.30am.