First Direct has told customers who want to pay with contactless cards that they must remove them from their wallets – in an apparent admission that the technology can go wrong.

The introduction of controversial “contactless” payment cards – where customers make payments of up to £20 by briefly touching their card to a reader and do not enter a Pin number – has caused at least one bank to alter its customers’ terms and conditions.

First Direct, the offshoot of HSBC, has written to its customers saying “we have made changes to clarify that if you have a contactless debit card you must remove it from your wallet or purse before using it to make a contactless payment.”

This change seems a response to the reported cases of mistaken payments, where money has been taken from peoples’ accounts without their knowledge but where they think they brushed against a reader by accident.

First Direct offered no further written explanation to customers. But a spokeswoman for the bank admitted the change was being brought in to prevent payments being made accidentally. She said: “If you don’t remove cards from your wallet there is a danger the payment may be taken from the wrong card. It could be a bit of a nightmare if it came from a card where there wasn’t enough money.”

The banking industry has previously downplayed such fears. Around 40million contactless cards are in issue and an estimated 100million payments will be made using them this year. Almost all banks are rolling the technology out automatically, as and when customers’ cards are renewed. Cards with the “wave” logo pictured above are enabled for these types of “one-touch” transactions.

Fears of the safety of the technology surfaced in May this year when customers of Marks & Spencer claimed payments were taken without their knowledge. M&S was one of the first large chains to deploy the technology en masse at its checkouts. Many others have followed suit including sandwich chains and restaurants.

There were also fears the cards were vulnerable to fraudsters carrying readers which, if placed near enough to the cardholder’s wallet or pocket, could capture data.

UK Cards Association, the trade body for the payments industry, said: “Problems are exceptionally rare, with only a handful of cases reported where the wrong card has been debited when accidentally placed very close to a contactless card reader.”

The spokesman added: “The technology is extremely robust, has been thoroughly tested and is working as expected. Payments can only take place where the card is placed within 5 cm (2 inches) of the terminal.”