Police said Wednesday they had seized enough cocaine to supply New Zealand for 30 years, after snaring a massive bundle of drugs floating in the Pacific Ocean.

New Zealand police commissioner Andrew Coster told reporters the haul -- containing 81 bales of cocaine -- weighed 3.2 tonnes and had a street value of around $316 million.

"This is the largest find of illicit drugs by New Zealand's agencies by some margin," he said.

Officials believe the drugs were dropped at a "floating transit point" in the Pacific Ocean, where they would have been picked up and taken to Australia.

A police photo showed the massive haul was bound by netting and covered in yellow floats. Some of the bales had a Batman symbol on them, and the packages of cocaine inside are labelled with what appeared to be a four-leaf clover print.

"We believe it was destined for Australia, where it would have been enough to service the market for one year," Coster said.

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

A naval boat intercepted the bundle, which was drifting hundreds of kilometres northwest of New Zealand, thanks in part to intelligence from the "Five Eyes" alliance.

The decades-old intelligence-sharing network comprises the US, Canada, Britain, Australia and New Zealand.

Coster described the bust as a "huge result" for police in both New Zealand and Australia.

"There is no doubt this discovery lands a major financial blow right from the South American producers through to the distributors of this product," he added.

Officials said it was too early to say where the drugs came from.