Scotland’s three main banks, Clydesdale, Royal Bank of Scotland and the Bank of Scotland were initially told the new £5 notes were vegan-friendly.
After a more detailed analysis, manufacturers De La Rue acknowledged the presence of animal derivative equivalent to a maximum of 0.003% per banknote.
More than 100,000 people signed a petition after the Bank of England admitted its new £5 contained a small amount of a tallow - a product which contains animal products.
Tallow is also widely used in the making of soap and candles.
Vegans, vegetarians, Hindus, Sikhs, Jains and others have urged a ban be imposed on the new notes.
The new polymer banknotes are more durable than the present cotton ones, and expected to last on average five years compared to the two-year lifespan of current banknotes.
A statement, made on behalf of the three banks, through the Committee of Scottish Clearing Bankers, said: “Royal Bank of Scotland, Clydesdale Bank and the Bank of Scotland have been contacted by De La Rue following its announcement this afternoon and are in full dialogue with the manufacturer.
“None of the banks were previously aware of the potential presence of animal products in the manufacture of its polymer notes and recognise and understand the concerns of customers. We have asked De La Rue to investigate why this has happened as a matter of urgency.
“De La Rue is working with its suppliers and will keep all banks informed as it continues its investigation.”