WASHINGTON — It's time the federal government began protecting Americans from unsafe credit cards, just like it does from unsafe toasters and cars, consumer groups told a Senate panel last week.

Credit-card companies routinely offer cards that have been loaded up with tricks and traps that consumers don't know about or understand, causing millions of Americans to become hopelessly mired in debt, Harvard law professor Elizabeth Warren told the Senate Banking, Housing and Urban Affairs Committee during an oversight hearing on the credit-card industry.

Those tricks and traps include hiking interest rates when a cardholder falls behind in payments to other creditors, charging fees for payment by telephone and a practice called double-cycle billing. That's when a cardholder, for example, pays off $90 of a $100 charge but in the following month the bank charges interest on the entire amount rather than on the $10 balance.

It takes a lawyer to figure out the terms and conditions of most credit-card contracts, Warren and other consumer advocates complained. Increasingly, credit-card companies are targeting college students, military personnel, the elderly and the handicapped in their mass pre-approved solicitations, the critics said.

"No one has to be an engineer to buy a toaster in America, no one has to be a crash test expert to buy a car," said Warren, a best-selling author of consumer books. "Cheap shortcuts that boost (credit-card company) profits but leave consumers at risk should be banned from this market."

Americans' use of credit cards has exploded in the past 20 years. In 1980, consumers used 100 million credit cards to purchase $69 billion in goods and services. Last year, they used 700 million cards to buy $1.8 trillion in goods and services. About 40 percent of credit card holders pay off their debt every month. The average credit card debt for households that carry a balance is $13,000, Robert Manning, professor of consumer finance at the Rochester Institute of Technology told the committee.

At least two senators, Daniel Akaka, D-Hawai'i, and Carl Levin, D-Mich., have said they will introduce legislation this year to rein in the credit card companies.

But Richard Vague, CEO of Barclays Bank Delaware, said Federal Reserve Board studies consistently show that 90 percent of consumers are happy with their credit-card issuers. He agreed that credit-card disclosures need to be made more readable. He cautioned against Congress imposing legislation that would control prices and limit products.

"(Price controls) would likely result in an increase in other costs associated with credit cards, reduced benefits or, more probably, a reduction of credit availability to those who are on the lower end of the credit spectrum," Vague told the committee.

A recent Government Accountability Office report found that because of competition among card issuers, more Americans have access to credit than ever before, and credit-card interest rates have declined from roughly 20 percent 15 years ago to 12 percent today.

"They are an important component of a financial services industry that is the most dynamic and innovative in the world," said committee chairman Christopher Dodd, D-Conn.