TICKET machines for the Glasgow subway “cannot accept” new bank notes which have been issued featuring King Charles.
The newly-introduced notes, which feature the monarch for the first time, cannot be used at automatic machines, SPT said.
The £5, £10, £20 and £50 notes went into circulation on Wednesday, June 5.
However, bosses said customers must use the ticket office rather than automatic machines if they want to use the new notes.
An SPT post read: “Please be aware, our ticket vending machines are unable to accept new King Charles bank notes.
“If you wish to use them as payment, please use them at the ticket office.”
The Bank of England said notes that feature the portrait of Queen Elizabeth will remain legal tender and are co-circulating alongside King Charles III notes.
A statement said: “New King Charles III banknotes will only be printed to replace those that are worn and to meet any overall increase in demand for banknotes.
“Our approach is in line with guidance from the Royal Household, to minimise the environmental and financial impact of this change.”