Launched via BNZ Twitter, the dual release quickly raced to the number one spot for financial apps in Apple's iTunes store.

BNZ says the uptake is gratifying, coming after the bank invested strategically in the assembly of a mobile banking software team at its head office in Wellington. The team are supported by various disciplines from across the bank and have developed the BNZ mobile banking solution from the ground up.

BNZ chief operating officer Stephen Mockett says: "Since we launched on Thursday the feedback has been flowing in from customers over Twitter and Facebook. Customers loving both the design and the convenience mobile banking provides. It backs our investment in this area and is a real credit to the quality of work our Wellington-based BNZ development team has produced."

The rapid uptake of mobile banking applications in New Zealand is mirrored in other markets, as smart phone use escalates and users latch on to the convenience offered by pocket banking.

According to a new study By Canadian analyst house Solutions Research Group, more than 2.5 million people in Canada are now using mobile banking applications, representing a market penetration of 38% of all smart phone users with data plans nationally.

"Considering that the first bank app was introduced only 14 months ago, this is a very fast rate of adoption," SRG analyst Kaan Yigit, told the Globe and Mail. "This is one of the fastest adoption rates [for a new technology] I've seen in 10 years."

Online banking took more than four years to reach a similar level of market penetration in Canada, he adds.