BASLE, Switzerland -- Gerda Dietz leafs through a thick bundle of U.S. $20 bills and suddenly pulls one out.


The bank note is an unusually clumsy counterfeit. It has been made by sticking together bits of various notes and its main section comes from a humble $1 bill.


Dietz, a controller in Swiss Bank Corporation's bank-note trading department, has recorded another little triumph in a relentless battle against forgers.


"There are more and more forgeries these days and they're getting more professional all the time. They are becoming harder to detect," said Leo Haener, head of SBC's bank-note despatch section.


Forged notes are handed to federal police, who received 4,706 reports of counterfeits last year, almost double the 1992 figure of 2,541. The Swiss National Bank plans a campaign in October to make the public more aware of the problem.


Police had a major success last October when $12 million in forged $100 notes was seized in Switzerland. The notes came from a printing press near Zurich. Four people were later arrested.


SBC and the other big Swiss banks, Union Bank of Switzerland and Credit Suisse, have unrivalled experience in detecting counterfeits as the country is the world's biggest center for bank-note trading.


Each day up to a ton of folding money, roughly a million notes, crosses the tables of SBC's bank-note department. Dietz and the other 11 checkers each count several thousand notes during an eight-hour shift.


The money has been bought from or sold to other banks in Switzerland and abroad.


Summer is the busiest time as tourists buy foreign bank notes for holidays abroad. SBC trades in about 100 different currencies but the heaviest turnover is in dollars, German marks, French francs and Italian lira notes.


Dollar notes are the easiest to forge as they are all the same size with the same black and green colors and are technically behind most other countries' notes in safeguards against counterfeiting.


The latest trick to combat forgers is to incorporate kinegrams, pictures similar to holograms that change according to the angle from which you look at them. Austria already uses them in its notes and Switzerland will follow next year.


But forgers, who usually use color copiers or offset printing facilities for their work, will probably take the new device in their stride.


"Forgers always find a way. A year ago I was at a Bank of France presentation of new notes that they said could not be forged. We have since found counterfeits of them. Anyhow, the normal person doesn't look for a kinegram," said Armin Weisskopf, SBC director for foreign bank notes.


While other areas of banking increasingly use computers, bank-note departments continue to rely on manual labor.


"It's still the case that most forgeries are found by feeling and looking at the notes and not by using machines," Weisskopf said.


Dietz has been doing it for 20 years and little escapes her notice.


She shows a Ffr500 note which would fool most people. But her expert fingers notice instantly that the paper has not the right feel and her eyes see the print is fuzzy.


"Almost every day I find at least one forgery," she said.