Customers began complaining about being unable to access the banks’ websites and smartphone apps from around 4am on New Year’s Day.
The three companies, all part of Lloyds Banking Group, apologised before the issue was resolved by around midday.
A spokesperson for Lloyds Banking Group said: “Internet and mobile banking is now back to normal. We’re sorry that some of our customers had issues with it this morning.”
More than 11 million customers Lloyds Banking Group customers use its digital banking services. The representative for the group said could not confirm whether all were affected by the crash.
It is understood the problem was an internal issue and not a cyber-security one.
Hundreds of customers took to social media to express their frustration this morning.
One wrote on Twitter: “Will online banking be back up for tomorrow? It’s direct debits day for most people tomorrow and how can they know what’s going on their accounts if they can’t see it?”
Another wrote: “Any chance of an estimated time this might be resolved as I need to send money to my son who needs to get back from Liverpool?”
Many complained they had not been given any “timescale” for when online services will be back up and running again.