New Zealand's new banknotes will feature a "brighter, more modern look" and a host of new security features, the central bank said today, as it unveiled its first major currency upgrade since 1999.

The new notes will be released into circulation progressively between October 2015 and April 2016, and feature larger print and greater colour contrast between notes when compared to the existing series.

"The sharper and more colourful pictures on the notes bring flora, fauna, landscapes and history