Image copyright Brent Tandy/DOC Image caption File photo of a little blue penguin in its burrow

Three little blue penguins have been stolen from their burrow in New Zealand, say conservation officials.

Two men were seen using a crowbar to prise rocks off the penguins' burrow in Hawkes Bay and then hook the birds out by their neck.

One of the penguins died in the process and was left behind, but two were taken away.

Little blue penguins are the smallest breed of penguin and are a protected species in New Zealand.

Authorities believe the thefts might be an indication of a smuggling operation.

"We are really concerned as we believe this might not be a one off," said Department of Conservation (DOC) Hawkes Bay Compliance Officer Rod Hansen.

"The very next day another penguin was found dead floating nearby and it appears to have died from a head injury."

The theft was carried out at night on on 24 January. The DOC said they received reports of two men seen digging into the burrow while a woman held a torch.

It is not clear where the birds were taken to and the suspects have not yet been identified.

Image copyright Getty Images Image caption Little blue penguins are the world's smallest species of penguins

The DOC said the theft was "particularly disturbing".

"It is a very vulnerable time for these wee penguins. They moult from January through to March and stay in their burrows for protection... [this] further suggests the poachers knew exactly when best to target the birds," said Mr Hansen.

Little blue penguins, which typically measure just over 25cm tall and weigh around 1kg, are the world's smallest penguin.

The population of little blue penguins is declining in New Zealand and anyone found committing offences may be jailed up to two years and fined up to NZ$100,000 (£52,000; $68,500).