In a victory of consumer groups over financial services companies, bankruptcy legislation working its way through the Senate would require credit-card companies to warn consumers that paying the minimum amount due will add significantly to their interest costs.

The industry-backed bill, which the Senate will vote on next week, would make it harder for consumers to wipe out their debts through bankruptcy. It is similar to legislation passed last year by the House.

But in last-minute maneuvering, Sen. Paul S. Sarbanes (D-Md.) succeeded in pushing through an amendment opposed by the industry. It would require credit-card billing statements to warn consumers about interest costs and provide toll-free phone numbers where they can learn how long it would take to eliminate a balance when paying just the minimum amount required each month.

Before the Sarbanes amendment, the bill said that any company that provided a toll-free number with details about balance repayments would not have to tell consumers about the telephone number or that the information was available. That, Sarbanes argued, amounted to a huge loophole that defeated the purpose of having the toll-free number.

Democratic and Republican leaders expect the bill to pass by a wide margin as early as Tuesday. But it is unclear whether the consumer-disclosure requirements will make it through the process of reconciling the Senate and House versions of the bill, consumer groups and congressional staffers say.

Particularly opposed to the amendment is Sen. Phil Gramm (R-Tex.), chairman of the Banking Committee, who, according to Gramm spokeswoman Christi Harlan, fought it on behalf of American Express Co. on the grounds that it is "an unnecessary government intrusion in private business."

American Express spokeswoman Gail Wasserman said the company didn't lobby against more disclosure and is happy to put the warning on its bills.

Proponents of the bankruptcy reform bills contend that legislative changes are needed to close loopholes in current law that the industry says are exploited by people who can afford to repay debt. In general, the House and Senate versions of the bill would require more people to repay large portions of their debt.

Credit-card companies, banks and other retail lenders say bankruptcy legislation is needed to prevent people with good incomes from unfairly using Chapter 7 of the bankruptcy code to wipe out their debts. Creditors say they must charge higher fees to people who handle debt responsibly to pay the cost of those who abuse bankruptcy laws.

Consumer groups and many Democrats say lenders' liberal credit policies and aggressive sales practices have been equally responsible for putting many Americans over their heads in debt. They say any legislation also should force credit companies to be more responsible by providing more consumer information.

But the industry has fought attempts to require credit companies to make it clear how much consumers are being charged in late fees and how long it would take to pay off by making the minimum payments. The credit industry says it would be too costly and burdensome to its computers to give consumers monthly updates on such information--and it argues that the information would be meaningless to consumers anyway.

In 1998, 1.4 million personal bankruptcy petitions were filed, an increase of 3.6 percent over 1997 and 94.7 percent over 1990. About 70 percent of those bankruptcies were filed under Chapter 7, which permits most debts to be erased, rather than under Chapter 13, which requires a partial repayment over time. Recent studies have suggested that personal bankruptcy rates are leveling off, however.

According to a study funded by the American Bankruptcy Institute, a nonprofit, nonpartisan educational group, about 3 percent of the people who file under Chapter 7 could repay a portion of their debt under Chapter 13. The credit industry has estimated the number to be 10 percent to 15 percent.

Jeff Tassey, spokesman for the American Financial Services Association, a lobbying group for large, diversified consumer lenders, said his organization isn't happy with the Senate bill's requirements on warning consumers about minimum payment costs. But he said, "We're not fighting it."

Travis Plunkett, spokesman for the Consumer Federation of America, a nonprofit consumer advocacy group, said the disclosure requirements are vastly inadequate. "The bankruptcy bills tilt towards creditors in almost every way," he said. "It's just not good enough to say, 'By golly, it's going to take a while to pay this off, so call this 800 number for more information.' "

Under the Senate disclosure requirements, many credit-card companies would also have to include on their billing statements charts that would show consumers the compounding effect of interest.

The charts would show, for example, that a $1,000 credit-card balance paid off at a rate of 2 percent a month and carrying an interest rate of 17 percent would take 88 months, or more than seven years, to pay off.

CAPTION: Sen. Paul S. Sarbanes (D-Md.) succeeded in pushing through the credit-card amendment.