UK banks have warned customers that sharing access to fingerprint authenticated transactions is the equivalent to giving someone a PIN number for a bank card.The banks Lloyds, HSBC, First Direct have all said that users must ensure to only register their own fingerprints to authorise transactions.Beyond using fingerprints for Touch ID-enabled apps, British banks including Barclays have joined the Apple Pay service, which authenticates transactions with fingerprints.Santander, NatWest and Royal Bank of Scotland customers were the first to be able to use their accounts with Apple Pay,Having other people's fingerprints on your device “will be treated as you failing to keep your card details and security details safe”.Most models of iPhone carrying the Touch ID facility allow up to 10 prints to be stored.