Banks and other lenders nationwide, seeking to reduce their debt exposure, are shutting off and limiting consumer credit card lines, even for many customers who carry low balances and pay on time.

As much as $2 trillion in consumer credit - nearly half of what is available - could be rescinded, according to an estimate by a prominent banking analyst. Just two years ago, institutions were handing out liberal borrowing lines to almost anyone. But now, drowning in debt and soured investments, lenders are seeking to stop consumers from running up big balances in hard times, bills they might not be able to pay.

The credit squeeze doesn't just limit spending potential; it can also damage cardholders' credit ratings by making them appear to be riskier borrowers. And in many cases, the institutions pulling back on credit took government bailout funds that were supposed to encourage them to lend more freely.

Diana Lawton, a 44-year-old freelance writer in Chelmsford, is one of those being affected by the change in credit-line policies. She said American Express Co. called her last week to say her two charge cards - one personal, one for business - had been frozen pending a "financial review." Lawton, who had been using the personal card since 1988, said she was stunned. The company offered no explanation, accord ing to Lawton, but told her she could apply for reinstatement by submitting two years of income tax returns, along with three months of pay stubs and bank records.

Outraged at having to undergo a 10-day investigation of her finances, Lawton canceled the cards. "I know the economy's bad," she said, "but this is just shocking to me."

American Express, which has received $3.4 billion in federal bailout money, declined to discuss Lawton's situation. Lisa A. Gonzalez, a company spokeswoman, said that on "isolated occasions" it asks card members to provide financial information. "Though we continually look at the credit limits we offer card members and review them on a case-by-case basis, we are being more targeted in response to economic conditions," Gonzalez said. "This may also include cancellations."

Most bankers won't offer details about the cutbacks, but acknowledge they are happening. Betty Reiss, a spokeswoman for Bank of America Corp., the nation's second-largest card issuer, said, "We're taking a more aggressive look at accounts in order to control risk in the current environment." The bank is one of the biggest recipients of federal bailout funds - $45 billion.

As far back as July, 60 percent of card issuers reported they were constricting lines of credit, according to Javelin Strategy & Research, a Pleasanton, Calif., firm that tracks the credit card industry. And a Federal Reserve Bank survey in October, the latest available, found the same portion of bankers reporting tighter lending standards on credit cards.