The Commonwealth Bank has apologised after an all-day glitch locked thousands of customers out of their accounts on Monday.

The bank, which is Australia’s largest, said multiple services were affected nationwide when the outage hit about 7am (AEST).

Many customers were still having trouble accessing their money even after 4pm, when Comm Bank said the issues had been resolved.

“Services are recovering following intermittent issues that some customers experienced across our banking services today,” it said in a social media update.

“We can confirm we have identified the cause of the issue and services are being restored.

“We are very sorry for the inconvenience this has caused. We know how much customers depend on us and sincerely apologise to those who have been impacted today

“Please note there may be delays in some payments as we continue to bring services back online.”

The bank did not detail what had caused the Australia-wide outage. Earlier it said its call centres were flooded by worried customers.

CBA said its branches were open but staff there would have no further details for worried account-holders. There were multiple reports that cash withdrawals via tellers had been limited to $300 a customer on Monday.

Affected customers were urged to check the bank’s website for the latest updates.

CBA is Australia’s largest bank, with more than 15 million customers. Its mobile banking app CommBank has 7.7 million users.

Tweet from @CommBank

Website Downdetector showed outages had been reported by thousands of customers. Most had reported problems with online banking and using the app.

Customers who were left in the lurch at the till or when making payments turned to social media to vent their fury.

“Commonwealth Bank down. Father tried paying his credit card bill. Was told all their systems down, to come back in 30 minutes. Anyone else having problems?” wrote one Twitter user.

“Yep, it is, a fact I discovered only after completing a week’s shopping. Card didn’t work either,” wrote another.

Tweet from @dipu522035

Other customers reported the issue had also affected ATMs.

“Comm Bank, [it’d] be good if you gave customers a heads-up as to why we can’t access Netbank? People are also claiming zero funds showing at ATM even though they have funds?” tweeted one customer.

“Netbank is down. Absolute chaos is in progress. First day of school holidays, and CommBank has had a meltdown. No online transfers, ATMs, or EFT. Don’t try calling, lines are jammed,” wrote another.

Even after the bank’s 4pm update, customers remained concerned.

“I appreciate it must have been a stressful day but we will need a lot more explanations about what went wrong,” one said in response.