New Zealand's navy has intercepted a floating haul of cocaine in the Pacific Ocean in what the country says is its largest drug bust ever.

The stash - weighing total 3.2 tonnes (3,200kg) and worth NZ$500m (£263m; $316m) - was found drifting hundreds of kilometres northwest of New Zealand.

Police believed it was destined for Australia, where it would have been enough to serve that market for a year.

The packages were strung up with buoys and some labelled with a Batman symbol.

Pictures released by New Zealand police and defence officials also showed cocaine packets labelled with a black four-leaf clover symbol.

These were the "trademark logos" for the drug producers, believed to be in South America, said New Zealand officials.

"This is the largest find of illicit drugs by New Zealand agencies, by some margin," said New Zealand's police commissioner Andrew Coster on Wednesday.

"It is more than New Zealand would use in 30 years," he added.

New Zealand's navy deployed a vessel to retrieve the massive shipment last week, which comprised 81 bales of cocaine.

They were brought to Auckland in New Zealand's North Island on Tuesday and taken to a security facility to be documented and destroyed, officials said.

"We believe we have dealt a significant blow to an international criminal syndicate's operation," Mr Coster said.

Authorities did not disclose details of the operation or how they found the drugs. But they said their partners in the Five Eyes intelligence group - which includes Australia, the UK, Canada, and the US - had provided assistance.