Benny Higgins said the bank has temporarily stopped online debit card customer transactions as a “precautionary measure”.

Current account customers will still be able to use their cards for cash withdrawals, chip and pin payments, and all existing bill payments and direct debits will continue as normal.

Tesco Bank confirmed that over the weekend 40,000 of its current account customers experienced fraudulent activity and 20,000 suffered some sort of financial loss.

Higgins said: “We apologise for the worry and inconvenience that this has caused for customers, and can only stress that we are taking every step to protect our customers’ accounts. That is why, as a precautionary measure, we have taken the decision today to temporarily stop online transactions from current accounts.

“We can reassure customers that any financial loss as a result of this activity will be resolved fully by Tesco Bank, and we are working to refund accounts that have been subject to fraud as soon as possible.”

Money has been taken from my account – what should I do?

Tesco Bank said it has texted all affected customers to inform them of the fraudulent activity and is working to ensure any customers who have experienced financial loss as a result of this activity are refunded as soon as possible.

However, if you haven’t received a text message, it is still best to check your account.

If a customer requires access to emergency funds immediately to cover any loss, Tesco Bank is offering an emergency cash process at the 298 stores which have deposit and withdrawal facilities available at the Customer Service Desk. Customers can withdraw up to a maximum of £200 per day through this method.