Fancy printing your own banknotes? Think again. University professors are out to get you.

A team of academics from Leeds University has created an ink that changes colour when copied or scanned. Real notes made with the new ink change colour by the heat from a copier or scanner, preventing forgers from getting the tones right.

The invention is a timely one. Last month, the Bank of England halted the issue of a new five pound note after tests showed that the notes' serial numbers easily rubbed off, despite it being intended to be Britain's safest yet.

"Banknote forgery is quite prolific at the moment," said Prof David Lewis, the Leeds academic who heads the team developing the new ink.

The advent of euro notes and coins at the start of this year heralded a flurry of "funny money", which forgers could circulate as people were unfamiliar with the new notes.

At the start of the year, French police arrested a woman and her son for using a fake euro note, while similar counterfeit euro notes emerged in Germany, the Netherlands and the Republic.

The amount of phoney cash in Britain represents well under 1 per cent of total currency in circulation, but officials say people should be on their guard.

Forgers sometimes use sophisticated photocopiers to copy or scan notes, but Prof Lewis said his team's new ink would render this impossible.

He cited examples where it would be hard to check the authenticity of banknotes, such as in nightclubs, where it would be difficult to verify the hologram features on pound notes.

His team has linked up with British ink manufacturer Xennia to set up a joint-venture company to develop the forger-busting ink.

Prof Lewis said they could bring their new ink to market within a year.