A woman who was part of the group that discovered $3 million worth of cocaine on an Auckland beach says her dogs urinated on the drugs.

Nineteen sand coated bags of cocaine washed up on West Auckland's Bethells Beach around 4.30pm on Wednesday. Police later estimated the drugs to have an estimated street value of about $3m.

A woman who was part of the "team effort" discovery, said she was walking her two dogs when she saw the "strange shaped thing" on the beach.

Supplied/NZ Police About 19 sand-covered packages containing cocaine have been found on Bethells Beach since Wednesday afternoon.

The woman, who Stuff​ agreed not to name, said the drugs were wrapped in blue packages inside a netted bag.

READ MORE: Cocaine worth $3 million discovered on West Auckland's Bethells Beach

The police were phoned and shortly after an officer arrived, tested the contents of the package and confirmed it was cocaine.

Supplied/Joshua Hall Bethells Beach is a popular walking spot in West Auckland. (File photo).

In the meantime, the woman's dogs "did what they tend to do when they find strange things" and urinated on some of the packages.

"They peed on $3 million worth of drugs. They tried to mark it as theirs."

Detective Inspector Colin Parmenter said more packages could wash up.

But the woman said she doubted that, because it appeared the packages had been inside a net bag, which may have been opened by whoever reached the drugs first.

The drugs had probably been in the ocean for a while, she said, as there were shellfish on the packages.

She said the beach had some weird things wash up before - including dead whales and seals - but the drugs had been "quite an unusual event".

RNZ An estimated $3 million worth of cocaine has washed up on a rugged west Auckland beach, much to the surprise of locals.

"It was not what I was expecting to find on the beach, that's for sure. I was looking for seaweed [for her garden]."

However, she hoped people would not come looking for drugs, so as not to disturb birds currently nesting in the area, including the native dotterel.

Legal experts have warned anyone who tried to collect the drugs from the sand could find themselves being prosecuted.

The police Eagle helicopter would conduct a wider search of the area on Thursday and "regular patrols" would be sent out in coming days to check for more washed up items, Inspector Parmenter said.

"Our inquiries are ongoing to identify where these drugs have come from."

New Zealand was ranked as the most expensive country to buy cocaine in the 2019 Global Drug Survey.