NAB internet banking goes black

National Australia Bank has suffered an outage of its internet and telephone banking systems today.

A spokesman for the bank told iTnews that the issues started at approximately 9am.

While he said that phone banking services had been reinstated by 11am, the internet banking website continued to suffer downtime. It was restored at 4.15pm, according to a tweet.

"We had some issues with internet and phone banking related to the log-on process," he said.

The bank earlier posted messages to Twitter that it was "working to resolve the issue".  A message posted to its internet banking website blamed "very high levels of usage".

"Please try again later," the website advised. "Full service will resume as soon as possible."

The outage came a day after UBank, a division of NAB, reported a separate glitch.

"Our apologies to UBank customers who received duplicate emails & SMS, we are currently experiencing issues & are looking into it now," the bank told customers yesterday.

Last year, NAB suffered an outage after a "corrupted file" crashed its payment processing systems, affecting "millions" of people and causing flow-on affects for other banks.

A separate glitch at the end of last year saw customers unable to download a functional version of NAB's iPhone and iPad applications.