Eighty-three percent of the merchants who sell goods online say fraud is a problem, up from 75% who said so a year ago, according to a survey jointly conducted by CyberSource Corp., a vendor of software for online transactions, and Mindwave Research, an online research company. The survey polled 132 companies, including both corporations that sell exclusively over the Internet and those that sell goods online as well as at stores or through catalogs.

The survey also found that online purchases amount to 5% of all credit-card transactions, but amount to 50% of all fraud involving cards. “Online fraud continues to be a growing concern for merchants and they are taking it very seriously,” said William Donahoo, vice president of marketing at CyberSource.

The surveyors said that fraud rates, though growing, may soon peak. On average, the companies surveyed estimated that they lose 4% of their overall online revenue to credit-card fraud. That number is down from 5% a year earlier. A majority of corporations, 61%, said they are taking more precautions against fraud.

Fraud rates in new markets tend to level off after an initial spike. Credit-card association Visa USA, for example, says its internal data shows that 15 cents to 18 cents on every hundred dollars charged to Visa cards for mail order or telephone sales prove to be fraudulent. That number is down from the 25 cents to 30 cents of every hundred dollars spent in 1993, when mail-order and telephone sales were first catching on.

Internet purchases, along with phone or mail-order purchases, fall into a category called “card not present” transactions. Merchants bear the risk of fraud in these sales, and must absorb the cost of most claims.

But many merchants don’t realize they are liable for fraud in these transactions, the survey found. As many as 28% of those corporations surveyed either didn’t know who was responsible to absorb the costs or said that burden lies with the bank or credit-card company. But awareness is improving, the survey found. A year ago, 41% of merchants surveyed thought others were liable for bearing the costs of online fraud.

Banks, credit-card companies and merchants are taking steps to combat fraud. Visa USA, for example, announced this week a payer authentication service that will allow merchants to verify the user of the card during the checkout process. Cardholders who aren’t able to proffer a preregistered password during the checkout process won’t be able to complete the purchase.

Visa also has posted a series of merchant guidelines that spell out safe practices in storing credit-card and password information. Merchants who don’t comply with these guidelines by the first quarter of 2001 could face fines. The goal, according to a spokesman, is to “heighten consumer confidence” in online transactions.

CyberSource’s survey found that 52% of the merchants polled felt that customer concerns over online shopping would be eased simply by employing fraud-screening practices, and displaying the logos of such service providers on their Web sites.