The banking giant has confirmed that for one weekend a month until next January, online and telephone banking, as well as its smartphone app will be locked so that maintenance work can take place.

The disruption – affecting both retail and business customers – begins this weekend between 11.30pm on Saturday and 3.30pm on Sunday, though Barclays has not confirmed dates for the coming months.

While users will not be able to check their balance online or send money via the Pingit service, they will still be able to use their cards and withdraw money from cash machines.

Why is this happening?

Britain’s biggest banks – including Barclays – are being pushed to separate their everyday banking activities from their riskier investment-based activities, as part of new ring-fencing rules which come into force in January 2019.

The rules are an attempt to avoid another financial crisis, and will see these large banks essentially become two separate entities.

This change means that around a million banking customers will be issued with new sort codes and/or account numbers by their banks, and Barclays has said that the locking online banking over the next couple of months will help the bank get ready for the switching process.

The news comes in the same week that Barclays announced the closure of dozens of branches across the UK.