Aucklanders and Northlanders wanting to withdraw cash from ATMs yesterday afternoon were unable to between lunchtime and 2.15pm.
National Bank spokesperson Cynthia Brophy says the outage "affected the National and a few other banks from Auckland northwards".
Whose fault the outage was is unclear. Telecom spokesman Andrew Bristol says Telecom's events centre recorded no outages between 11am and 3pm, but Brophy says an internal National Bank email noted that National and other banks were working with Telecom to fix the problem, which was corrected by 2.15pm.
The National Bank's link to other banks' ATMs was also affected, Brophy says.
The internal email also mentioned that a switch was involved, she says, though whether a fault with a switch was the cause of the outage is unclear.