A number of banks have confirmed National Australia Bank's (ASX: NAB) unresolved technical glitch that occurred Wednesday had affected their transactions.

"NAB clears payments for HSBC in Australia, as well as other banks. As a result of the technical issues NAB is experiencing, the processing of some of our customer transactions has also been delayed," HSBC said.

ANZ Bank and Citi said their customers were also affected.

NAB in a statement today said "As previously advised NAB experienced some issues overnight on Wednesday 24 November which delayed the processing of some customer payments and transactions into accounts on Thursday 25 November."

"These transactions have now been processed."

"However, due to remediation work on completing this processing overnight, some payment processing from 25 November has also been delayed and will be processed during the day on Friday 26 November. This includes payments made both to our customers and in some cases from NAB to other banks' customers."

"We have commenced the processing of these delayed payments and transactions and they will continue to be progressively processed through-out the day."

The bank said it will provide further updates as things progress.

NAB's system is believed to have broken down by 4am, when many overnight payments are automatically processed. The outage, caused by a corrupted file is said to have affected both retail and wholesale transactions.