The Bank of England has said its new £20 notes will be made with palm oil - as long as the public agrees.
It launched a consultation on its new polymer bank notes after it delayed the new £20 note because of protests from vegans.
The Bank said its suppliers, Innovia Security and De La Rue, had found palm oil to be "the only practical alternative to animal-derived additives" but that it wanted to hear more opinions from the public.
Palm oil is itself the subject of considerable controversy, with an independent report by Efeca released alongside the Bank's consultation pointing out it is the fourth-highest agricultural contributor to deforestation, accounting for eight per cent of the damage done between 1990 and 2008.
The Bank's suppliers say palm oil offers a "mature supply chain and is available at a reasonable cost".
The Efeca report notes "plantation workers are often hired on a temporary basis and can suffer from low wages and poor conditions of employment and health and safety". There are also concerns the industry may be implicated in forced labour and child labour.
Environmental group WWF said palm oil production can be unsustainable and damaging to tropical forest, but it was encouraged by the Bank's consultation.
Emma Keller, agriculture commodities manager at WWF said: "People don’t want the bank notes in their pocket to come with such a high environmental cost. The bank must only source RSPO (Roundtable on Sustainable Palm Oil) certified sustainable palm oil or none at all.”
The Bank of England found itself at the centre of the unlikely controversy in November when it emerged the polymer mix in the new notes contained trace amounts of tallow (rendered animal fat).
The Bank admitted “there is a trace of tallow in the polymer pellets used in the base substrate of the polymer £5 notes.” The animal fat, sourced from beef, reportedly made up less than one per cent of the notes’ composition.
Hi Annie, there is a trace of tallow in the polymer pellets used in the base substrate of the polymer £5 notes.— Bank of England (@bankofengland) November 28, 2016
The revelation outraged vegans, forcing the Bank to launch a hasty review into whether to keep the notes. It decided to keep the notes in circulation owing to the £46m it had already spent on printing the new notes.
In February it said it would seek “further opinions” on replacing the tallow with a vegan-friendly substance for any new stocks.
The new £20 note will also be made using polymer. It will feature an image of the artist JMW Turner, although copies of the note have not yet been printed.
The Royal Mint, which is separate to the Bank of England, is also in the process of rolling out new one-pound coins, with a 12-sided design and multiple anti-counterfeiting measures. These include a hologram-like feature and a secret security feature.