By Leslie Goffe in New York

Known the world over for its distinctive green tones, the US dollar - or 'greenback' - is about to go through a major transformation.

US officials are concerned that widely accessible technology such as ink-jet printers and high definition scanners are making it easier to forge dollar notes.

They are planning to add new colours - including pink tints - to the notes in an effort to beat counterfeiters.

It is estimated that forgers have filtered up to $10m in fake bills into the US for each of the past ten years.

Opposition

"Most of the US paper notes circulate abroad..., and people abroad would probably feel uncomfortable"

Uta Wartenburg, American Numismatic Society

Jim Hagedorn, an official at the US Bureau of Engraving and Printing - the federal agency responsible for producing money - said the US Treasury believes it needs to re-design notes every seven to ten years to stay ahead of technology used to produce forgeries.

But despite the threat posed by forgers, many Americans are reluctant to see any changes to the greenback.

"I kinda like it the way it is," one man said. A woman agreed with him, praising "the good old money colour - green and white," she said.

"I don't know, multi coloured? I like the green," said another woman.

Foreign expectations

But the greenback has been through changes before.

In 1996 the Bureau of Engraving and Printing made what it called, 'security enhancements' to the currency - adding embedded threads that glow under ultraviolet light, micro-printing and colour-shifting ink - to deter would-be counterfeiters.

The new notes should be unveiled to the public by the end of the year

Uta Wartenburg, executive director of the American Numismatic Society, said any changes should take into account foreign expectations of what a US greenback should look like.

"Most of the US paper notes circulate abroad, it is only a very small number that is used in America, and people abroad would probably feel uncomfortable," she said.

"I remember a few years ago a huge one page ad in the Financial Times from the US Treasury saying when the new slightly, revised notes, were introduced with only minor changes, people in places like Russia got so freaked out, they thought they were forgeries," she said.

"This is the main problem why they really ought to change, because any of us could - with a good scanner and the right paper - do this," she added.

The new notes are still being designed. They are expected to be unveiled to the public by the end of the year and put into circulation by the summer of 2003.

The US Bureau of Engraving says adding colour to the bills will enhance their design, make them more recognizable and easier to use.

But they will, the bureau insists, still look very much like the classic American greenback.