On the surface, the new cash cards offered by Japan's Mitsubishi Tokyo Financial Group look like those issued by any bank, anywhere. It's the images of blood vessels stored inside them that makes them different.

Each card holds a map of the veins in a customer's hand, a unique vascular fingerprint.

At the automated teller machine, customers pop in their cards and place their hands over a scanner developed by electronics giant Fujitsu Ltd.

Within a second, the palm-size machine compares the scan with the pattern stored in the card's circuitry. A match means a customer is free to withdraw as much as $20,000, the maximum daily limit for the bank.

Biometric technology, which uses the characteristics of a body part to confirm a person's identity, isn't new. Fingerprints and eye scans have been used in the past. But Mitsubishi Tokyo, Japan's largest bank in terms of market capitalization, in October became the first to bring vein recognition to the cash dispenser.

Now, competitors Mizuho Bank Ltd. and Sumitomo Mitsui Financial Group Inc. are preparing similar cards using a competing technology from Hitachi Ltd. Even smaller regional lenders, such as Suruga Bank of Shizuoka, are using vein-based biometric technologies at their branches.

The United States, where $2.7 billion in fraudulent transactions occurred last year, is more accustomed to security breaches. In Japan, a wave of recent cash and credit card thefts is only recently transforming personal financial security into a national obsession. While the amount stolen in ATM fraud cases totaled only $9 million last year, the high growth rate -- fraud cases more than doubled last year -- is enough to mobilize Japan's technology experts to design a host of security gadgets.

For Japanese developers, Japan also is a test case for bigger potential markets abroad, including the United States.

Fujitsu, which began marketing its vein-recognition technology outside Japan this month, says it has received inquiries from more than 100 companies.

It hopes for global sales of about $800 million in three years.

It isn't clear how quickly palm-vein authentication will catch on in the rest of the world. The technology isn't cheap: Equipping a standard ATM with the hand scanner costs about $3,000. And customers still aren't accustomed to it.

Armrests had to be installed at Mitsubishi Tokyo ATMs because initial customers held their hands at different heights, confusing the scanners.

Generally, though, the system is simple to use. And while fingerprints may change if a person works with chemicals, veins in the palm do not.

"It's only a matter of time before this sort of verification technology is adopted by banks in major markets around the world," said Neil Katkov, an analyst at the Tokyo office of Celent Communications LLC, a financial services consultant. "It's one of the easiest-to-use biometric technologies for an ATM."

Fujitsu's machines work by shooting a beam of invisible light through a customer's hand. Part of that light is absorbed by the blood flowing through the hand, leaving shadows that create a map of the veins.

Fujitsu's researchers chose the palm because it is relatively unaffected by cold temperatures, which can cause veins to contract. There is no hair on palms, meaning there is nothing to obstruct the light beams. And because so many veins run through a palm, each person has a different pattern.

"There's a lot of information in here," said Akira Wakabayashi, a director of Fujitsu's biometric business department, pointing to his palm.

Development began four years ago, when Fujitsu researchers did a feasibility study on applying the company's advanced imaging technology to a biometric product. At first, Fujitsu thought the technology could be put into computer mice as a way to prevent unauthorized users from accessing workstations. It later considered deploying the technology in locks for condominiums, health clubs and automobile ignition systems.

Meanwhile, Mitsubishi Tokyo was looking for ways to differentiate its cash cards, which have just begun incorporating a Visa credit card. When the bank contacted Fujitsu in 2003, the technology company suggested adding palm-vein authentication to the bank card. Now, Mitsubishi Tokyo has installed 1,400 terminals across the country.

To encourage more people to use them, Mitsubishi Tokyo won't charge a fee for a standard card. Though less than 5 percent of its depositors currently use the secure cards, Mitsubishi Tokyo is aiming to get 5 million cards in use by 2008. It says it receives about 2,500 applications for the card each day.

The next step: folding the secure cash card into a cell phone for greater convenience. Already, NTT DoCoMo Inc., Japan's biggest mobile-phone operator, along with Mitsubishi Tokyo and Fujitsu, has developed a prototype of a cell phone with cash-card functions.

"The two things that every person on the street has are a cash card and a cell phone," said Shinji Munekuni, a spokesman for the bank. "Put them together and you might be able to get more business."