This $20 note design has already been circulated.

New Zealand's new $20, $50 and $100 banknotes will be revealed at a Reserve Bank event in Wellington on Monday.

Concept designs have already been circulated but this will be the first time the final design is made public.

The notes will go into circulation later in the year. A Reserve Bank spokeswoman said the full details of the rollout would be revealed on Monday.

It is the last stage of a revamp of the currency - new $5 and $10 notes are already in circulation. The process of redesigning the notes is estimated to have cost the Reserve Bank $80 million.

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The new notes are the same size and denominations as the current banknotes, and they will continue to be made of flexible plastic.

The themes of the notes are the same and the same famous faces remain on them.

But some of the security features have increased, a move the Reserve Bank says will help stop counterfeiting.

The old notes can still be used for as long as they are in circulation.

The $5 note is in the running for the International Banknote Society's (IBNS) Banknote of the Year award, against countries including Gambia, Ukraine and Sweden.

But there have been teething problems with the new notes. Some automated payment machines have refused to accept them.