If you are looking to invest in old New Zealand coins or banknotes, an Australian sale has the goods but you will need deep pockets.

A three-day auction of important Australian and world coins, medals and banknotes which began in Sydney today, features a range of New Zealand currency, long withdrawn from circulation but often selling for thousands of times their face value.

A 1935 threepence was expected to sell at the Noble Numismatics auction for at least $2000.

The coin was toned with full original mint bloom, said the auctioneers.

It was "uncirculated and rare in this condition, one of the finest known".

Another uncirculated coin, a 1935 George V Waitangi crown, was expected to sell for $4500.

It features George V on one side and a Maori warrior shaking hands with a British naval officer on the other.

Other coins were expected to bring more modest returns. A rare 1936 George V florin and a 1940 George VI florin were both expected to sell for $1000 and a 1935 George V shilling was expected to sell for $300. Several George VI half crowns from the 1940s were also expected to bring $300.

New Zealand pennies from the 1940s were expected to bring slightly less - up to $250 each.

The sale also featured rare and valuable New Zealand banknotes.

An extremely rare one pound note issued by the Bank of Auckland in 1865, was likely to sell for $12,500. It had some rips, had lost both upper corners and had minor edge tears but was otherwise on very good condition.

Another one pound note, issued by the Colonial Bank of New Zealand in 1891, was expected to bring $14,500 while a ten pound note issued by the Bank of New Zealand was likely to bring $17,500.

A rare specimen set of notes featuring a ten shilling note, a one pound, five pound and ten pound notes, was expected to fetch $22,500, while a specimen set of five notes of two, five, 10, 20 and 100-dollar denominations had a list price of $12,500.

New Zealand changed to decimal currency in 1967 and some of the early decimal notes, including $2 and $20 notes were likely to sell for between $400 and $600 although two consecutively numbered $100 notes had a value on them of $1600.