Key Points:

Opposition leader and aspiring Prime Minister John Key has joined the ranks of the country's richest people.

The National Business Review Rich List - released today - reveals Mr Key spent US$3.25 million ($4.36 million) on a holiday home in Hawaii, and has business interests in a luxury Aspen ski resort, the Jackson Mining Company, and former employer Merrill Lynch.

Mr Key - whose political ambitions are dissected in a special report in tomorrow's Weekend Herald - is among 134 men, eight women and 42 families on the Rich List who have a combined wealth of $44.426 billion.

The National Party leader scrapes on to the list by just meeting the $50 million threshold, but the NBR said if elected, he could rank as the country's richest Prime Minister.

Mr Key would not comment on his inclusion in the list, but NBR editor-in-chief Nevil Gibson said it had struck the magazine that no one knew how much the former investment banker was worth.

"Everyone knew he'd arrived back in New Zealand and had made a lot of money, but up until now, no one had really taken it too seriously so we set out to investigate his past and came up with some pretty interesting conclusions."

The NBR found that as well as owning properties in Auckland, Omaha Beach, Wellington, London and Hawaii, Mr Key is a heavy investor in the Dairy Investment Fund, a private equity investor focused on deregulating the dairy sector.

The magazine said he had, however, lost money when the Haunui Dairy Company - in which he owned 103,543 shares - was recently put into liquidation.

The NBR reported Mr Key's Hawaiian holiday house was bought in March and has since been redecorated.

Mr Key himself has not disclosed the value of the Maui property, and has said all his properties are owned by his family trust, meaning he does not have to declare them in the Register of Pecuniary Interests of Members of Parliament.

The Rich List shows that despite tough economic times, New Zealand's rich have got richer and the country now has a record eight billionaires.

Graeme Hart's wealth comes from timber and packaging, and he has more than doubled his fortune from $2.75 billion last year.

The NBR says the 53-year-old has joined the ranks of the "seriously wealthy", sitting just one spot below the world's top 200 Forbes list of billionaires - and higher than Donald Trump, Sir Richard Branson and Steven Spielberg.

This year, he bought aluminium brand Alcoa's consumer goods packaging companies for US$2.7 billion ($3.6 billion).

Mr Hart is $3.8 billion richer than the Todd family, who made their money in energy and investments, and are second on the NBR Rich List.

New to the ranks of billionaires is Lynette Erceg, widow of liquor baron Michael Erceg, and the first woman billionaire on the list.

She replaces Kathmandu clothing founder Jan Cameron as the country's richest woman and, according to the NBR, has started investing the proceeds of her late husband's Independent Liquor company in wine and property.

Among the top entries on the Rich List, stalwarts Sir Michael Fay, Douglas Myers and David Richwhite tie for 10th place, each with fortunes of $700 million.

Eric Watson and Mark Hotchin, heads of troubled Hanover Finance, are said to be worth $450 million (16th) and $200 million (40th), respectively.

The Vela family, the racing magnates in the news this week for alleged undisclosed donations of $150,000 to New Zealand First, are ranked 46th with $180 million. Sir Robert Jones is 30th with $250 million.