Nationwide Building Society 'resolves' online bank problems
Nationwide Building Society says the technical problems that hit its online banking services have been resolved.
"The Nationwide online bank and mobile banking app are now up and running," a spokeswoman said.
Users of the services were unable to access accounts for much of Sunday after scheduled maintenance overran.
Some customers complained on social media that cash machines and card payments were also affected, but the firm said they were working normally.
The spokeswoman said the maintenance should have finished on Sunday morning, but did not know why systems had not gone back online as planned.
"We apologise to our customers," she said.
Nationwide said it "typically has around 500,000 customers who log on online to use these services on a standard day".