According to a report in Reuters, a source close to the incident said some customers were unable to use payment services or check their account balance when the bank was targeted by a distributed denial of service (DDoS) attack. Mortgage payments were not affected by the incident.

DDoS targeting is often used by cyber criminals to bring down firms with a strong online presence. In Lloyds’ case, the website was besieged by large volumes of traffic from multiple systems, causing the server to go down.

A spokeswoman for Lloyds said: “We experienced intermittent service issues with internet banking between Wednesday morning and Friday afternoon the week before last and are sorry for any inconvenience caused.

“We had a normal service in place for the vast majority of this period and only a small number of customers experienced problems. In most cases if customers attempted another log in they were able to access their accounts. We will not speculate on the cause of these intermittent issues.”

Several major banking players have been hit by criminal cyber activity over the past few years including Tesco Bank, HSBC and Royal Bank of Scotland.

According to the BBC, the National Cyber Security Centre is working with the bank on the attack.