Lorella Doherty has picked up hundreds of little plastic balls on the beaches of New Plymouth.

Hundreds of plastic wrappers washing up on New Plymouth beaches have left a plastic-free campaigner mystified as to their origin.

Environmental and biological science graduate Lorella Doherty said she has been collecting the small square wraps on beaches between Port Taranaki and Waiwhakaiho River mouth in the past six months.

The amount had rapidly increased in the six weeks with more than 500 found, mainly around Ngāmotu Beach and close to storage facilities near the port.

ANDY JACKSON/STUFF Plastic campaigner Lorella Doherty with a portion of the plastic wraps she has collected on New Plymouth beaches.

Doherty collected a haul of 187 wrappers in under an hour recently.

The discovery is timely with July being selected as 'plastic bag free month.'

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ANDY JACKSON/STUFF The source of the plastic cheese wraps is a mystery.

Doherty said she had no idea where the plastic wraps had come from.

"They look to be cheese wrappers and we find them crunched up in the sand as though they may have been through a spin process, or washed down a drain," she said.

"It doesn't look as though it is a one off because I keep finding the wraps every time I come down to the beach.

ANDY JACKSON/STUFF Plastic campaigner Lorella Doherty has been picking up 100's of plastic cheese lunch wrappers on New Plymouth beaches in the past six months.

"Have they been deliberately dumped, washed down a drain, or blown in the wind?"

Doherty rang the Taranaki Regional Council and was told the wraps may have come from a shipping container.

"They said it would be impossible to find the source, it would be like finding a needle in a haystack."

Doherty is a strong advocate for using alternative packaging to plastic.

She formed Rethinking Plastic Revolution to raise awareness on social media to the amount of plastic used, and how to provide options.

Each week she organised a group of New Plymouth school pupils to pick up plastic rubbish from Ngamotu Beach.

In the past month the group had collected 10kgs of plastic - mostly straws, bottle caps, fast food cutlery, lunch wrappers and fishing gear.

Doherty took the plastic back to her home where it is sorted and either used for art murals, or disposed of in New Plymouth District Council rubbish collection.

"It's easy to point the finger at companies, or blame others but the real aim of my work is to ask people whether they support use of plastic, or non plastic items," she said.

"I want to find a solution and inspire school children to not use as much plastic."

Port Taranaki, Taranaki Regional Council and Fonterra were contacted whether they were aware of the plastic spill.

Fonterra said the waste did not come from one of their sites.

"We can confirm that all stock is accounted for at the New Plymouth cool store and we also don't break down any commercial packaging on site," a spokeswoman said.

"It appears highly likely this is domestic waste or refuse from a nearby food outlet."

TRC resource management director Fred McLay said the council had been contacted and were investigating.

A Port Taranaki spokesman said the company was also investigating.