Vegans are outraged after learning New Zealand banknotes uses tallow — rendered animal fat from sheep, pigs and cows — as a "slip agent" to prevent friction and static.

The secret ingredient of tallow has been used for more than a decade and only became public when Britain adopted the same technology to produce its £5 note last year, resulting in a UK protest movement.

NZ notes are made up with 1 per cent animal fat.

The news in the UK and Australia has caused a great deal of heated discussion online.

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"New £5 note isn't vegan. Was everyone's New Year's resolution to do ridiculously insane stuff like adding meat to money?" one commentator, Dan Hanks, wrote.

Another said: "So unnecessary! I will no longer be accepting these notes. Ironic I donated my first fiver to a Vegan sanctuary."

An online video recently posted to Facebook by social commentators Project Nightfall in Australia reveals tallow is used in Australian currency, as well as in bank notes from Canada, Malaysia, Singapore and other countries — a total of 23, including New Zealand.

"This video is not friendly to vegans, Muslims, Hindus or Jews" warns the video.

The video has attracted over 630,000 views, and provoked nearly 5000 shares, and over 700 comments.

"Tallow is essentially fat that can only be made from pig, beef (pictured) or lamb," the presenter in the video says. Photo / Getty

Some Facebook users were horrified by the news.

"That is really horrible to hear. But, we can all limit cruelty of animals in our daily life by going vegan and using cruelty free products. It's sooo easy."

"Hopefully spreading this video will help people know more about it!"

Others had a different point of view.

"Isn't it better to just use natural animal parts rather than creating synthetic versions of it? We are part of this giant ecosystem, if we don't eat animals, someone else / some other animals do."

But some religious folks were not too concerned by the disclosure.

"As an orthodox jew … we are not allowed to EAT pork. We can touch it and use it. It being in money is not a problem at all."

Tallow is already used in a number of household items such as soap, candles, plastic bags, moisturisers, and even some fabric softeners. It's also found in some aeroplane fuel and even in mobile phones. Animal byproducts are also used in many clothing and cosmetics.

- Additional reporting by news.com.au