Wellington, Feb 16 NZPA - A Tauranga businessman uncovered a flaw in Kiwibank's network when he accessed his bank account using someone else's eftpos PIN.

Mike McAvoy said he and the teller were horrified when he entered the wrong pin in a Tauranga branch last week but realised he could access his money, the Tauranga-based Sunlive website reported today.

Kiwibank communications manager Bruce Thompson said a remote set of circumstances led to the incident.

Simultaneously as Mr McAvoy was keying in the wrong PIN, someone for whom it was the correct PIN was accessing their account and this caused the glitch.

"We did have a system failure, we have identified it, we have explained how it happened and we have fixed it," Mr Thompson said.

"To get this type of thing is an extraordinary set of circumstances."