Democratic lawmakers challenged executives Thursday over rising late fees and other penalties and marketing practices they portrayed as predatory.

The credit card industry and its practices came under scrutiny at a session of the Senate Banking Committee. Several Democratic members of the panel are proposing legislation to require companies to provide more details to consumers on how long it will take them to pay off their debts if they make minimum monthly payments, and to rein in solicitations of college students.

Credit cards have become a ubiquitous and indispensable part of the culture, with an estimated 640 million cards in Americans' wallets and more than $1.8 trillion charged on them in 2005. Many depend on them to pay their bills and buy groceries or gasoline. But consumer groups and other critics say fees are excessive and information provided to consumers is confusing.

The banking industry maintains that credit cards are an essential element of the economy, providing convenience to consumers — at flexible interest rates according to the risk of the holder. Industry officials have acknowledged that the disclosure material provided to consumers could be improved.

"I would like to put the credit card industry ... on notice," said Sen. Christopher Dodd, D-Conn., the committee's chairman. "If you currently engage in any business practice that you would be ashamed to discuss before this committee, I would strongly encourage you to cease and desist that practice."

Banks and other credit card issuers "should take a long, hard look at how you treat your customers," he said.

Dodd, one of several Democrats in the Senate who are seeking the party's presidential nomination in 2008, has put consumer issues on the committee's agenda for this year.

If the industry doesn't improve practices on its own, legislation may be needed, he indicated.

Dodd and other senators questioned a panel of witnesses that included executives of Chase Bank USA, Barclays Bank and Capital One Financial Corp.

The executives defended their practices as fair and responsible. Most customers pay their bills on time, and only a small proportion of them represent a risk of default and are subject to punitive measures, they said.

Some members of the committee, mostly Republicans, said that while improved disclosure is needed, lawmakers should avoid imposing requirements or sanctions for the credit card industry that would amount to price controls.

"I think we should recognize that the market does work," said Sen. Bob Bennett, R-Utah.

A study by congressional investigators released in October found that fees for paying credit card bills late averaged $34, up from $13 in 1995, while some card issuers impose penalty interest rates of more than 30 percent on consumers who pay late or exceed the credit limit.

Among other practices cited at Thursday's hearing:

— Some credit card issuers use a billing method that charges interest on credit card debt already paid by the consumer.

— The massive solicitations mailed to consumers — an estimated 6 billion in 2005 — and targeting of college students and the elderly.