Officials at New Zealand’s Auckland Airport are facing a barrage of criticism after they ordered police to shoot a trainee aviation security dog that escaped onto the tarmac.

The dog, a 10-month-old bearded collie-German short-haired pointer cross called Grizz,  escaped early Friday morning and was causing delays at the airport when airport staff issued the kill order.

The incident has sparked international news coverage as well as angry criticism from animal rights groups and the public about why the dog was not tranquilised rather killed.  Some passengers said they would have been happy to see their flight delayed if the dog could have been saved.

The shooting came after officials had tried for more than three hours to capture Grizz, who was not on the runway when he was shot.  By that time, about 16 international and domestic flights had been delayed.

The dog was being trained to detect bombs and was just six months away from graduating. It was not known what spooked him.

A spokesman for New Zelaand’s Aviation Security Service (Avsec), Mike Richards, told the New Zealand Herald:  "All efforts to capture the dog were exhausted and the airport company had no option but to request police to shoot the dog."

"The handler and Avsec are naturally upset but do understand there were no other options, in the very difficult circumstances.’’

Avsec said Grizz was being loaded into the back of wagon about  4:30am when he escaped and ran on to the secure airside part of the airport through an open gate.

 He did not have a permanent handler so was less responsive and all efforts to recover him failed, it said.

“All of Auckland’s Avsec off duty dog handlers were called in and there was a massive effort to locate and retrieve him,’’ an Avsec statement said. “The fact that the incident took place very early in the morning did not help as it was pitch black for the first two hours and he could not be found.

“When he was located he would not let anyone near him and kept sprinting across the runways. We tried everything, food, toys, other dogs, but nothing would work. The area is too vast and too open to try and use mobile fencing.

“In these difficult circumstances the Airport’s Emergency Operations Centre team decided to have the dog destroyed. Avsec and the handler and members of the Explosive Detector Dog Unit are naturally quite shaken but understand the reasons for the decision.”