WASHINGTON — As the fall semester beckons and financial aid from parents and the government runs dry, more college students are turning to credit cards to pay not only for their textbooks, meals and transportation but also for tuition.

A recent survey by U.S. Public Interest Research Groups found that two-thirds of college students have at least one card, 70 percent pay their own monthly bills, and 24 percent have used their cards to help pay tuition.

That helps explain why the average survey respondent will graduate with more than $2,600 in credit card debt, and those with student loans will owe nearly $3,000.

In recent congressional testimony, a card industry representative said that two out of three students paid their card balances in full each month.

However, concern about college students' credit card debt has led regulators, lawmakers and consumer advocates to question whether schools are making it too easy for card companies to market their plastic to students.

Of particular concern are exclusive agreements in which card companies and banks pay millions of dollars to schools or alumni associations for preferential treatment with their card-marketing efforts. The perks can include prime marketing space in high-traffic areas on campus or the use of a school's name and logo on their cards.

Three hundred of the nation's largest universities collectively pocket more than $1 billion a year on these marketing deals, said Robert D. Manning, the director of the Center for Consumer Financial Services at the Rochester Institute of Technology, in Rochester, N.Y.

The New York attorney general's office is investigating the practice nationally.

The agreements are usually confidential and often require the school to provide students' personal contact information.