Zespri is pursuing legal action in China to stop the spread of pirated kiwifruit cuttings.

The company's Gold Three variety was developed after 10 years of work with Plant and Food Research and is a much-valued strain of kiwifruit for the firm.

Zespri senior executive Dave Courtney says he first became aware of unauthorised plantings of G3 a few years ago.

It was now estimated 2500 hectares of illegal plants are under cultivation in China.

Dave says this was not a commercial threat for now but could become one if plantings spread further.

"So we are pursuing legal action - we are putting the blocks together to take civil action against some parties there," he says.

This case is believed to be breaking new ground in China, which has incurred repeated complaints about breaches of patents or copyright from many different countries.

"We will be one of the first to pursue plant variety rights in China," says Dave.

"We will have to step our way through it ... but where we have had trademark infringements in China we have had support from the authorities to rein that back in, so we are comfortable that we have the right channels to talk to."

Zespri has already gone to court over this matter in New Zealand, seeking $70 million in damages against parties alleged to have breached its trademark. A verdict has not yet been reached in that case.

-RNZ/Eric Frykberg.