The nation's credit squeeze is beginning to affect availability and prices of student loans offered by private lenders, according to a survey of hundreds of private colleges and universities released yesterday.

The National Association of Independent Colleges and Universities found that among surveyed schools that have received information from preferred lenders, nearly half have been told to expect tighter credit requirements.

One in five of those schools reports that at least one of its lenders is raising interest rates.

There is no evidence so far that students have had trouble landing a loan, the organization said. Nevertheless, the group says its findings -- including reports that lenders have stopped offering some loans -- are an early warning sign of possible trouble ahead this fall.

The issue will be hitting the radar screens of families from now through August as they begin securing these loans, usually the last piece of a student's financial aid picture to come together.

"The data collected serves as a warning flare," association President David L. Warren said.

"There is widespread uncertainty about the full extent of the credit crunch and what its impact on student borrowers will be, and what safeguards the federal government will have in place to avert a crisis," he said. "Institutions are looking for national guidance."

For private student lenders, the squeeze that began last year with housing woes and sub-prime mortgage defaults is only part of the problem.

Along with market turmoil, federal law changes enacted after last year's private loan scandals have eroded lenders' profit potential. They are answering by trimming discounts that had made their loans in many cases significantly less expensive than those from the Federal Family Education Loan Program, called FFELP, which includes Stafford Loans.

At one area school, Robert Morris, officials said they, too, are hearing from lenders that things are tightening.

Janet Lawson, the school's student loan program administrator, said the problem isn't with federal programs including subsidized and un-subsidized Stafford loans or Plus loans. Rather, it's students, especially those with marginal credit ratings, who must borrow from purely private sources. "They're definitely tightening up on lending criteria," she said. "They're requiring better credit scores or maybe co-signers where they weren't previously requiring a co-signer."

Like their counterparts at other schools, Robert Morris students depend on private loans for the share of their education costs not covered by government, institutional or other aid. Nearly 20 percent of the university's 5,000 students have private loans collectively worth $16 million.

In this state, the student credit squeeze hit home earlier this month, when the Pennsylvania Higher Education Assistance Agency temporarily suspended activity as a lender in the FFELP program, saying bond market turmoil had made it harder to raise capital to make loans.

Experts have said students attending proprietary schools and higher-priced private campuses are more vulnerable, but public campus officials are getting jitters, too. Days after PHEAA's announcement, Penn State moved to ensure availability of loans for its students by becoming a direct provider of federal student loans.

The survey released yesterday drew responses from 315 institutions, from Ivy League campuses to small religious colleges. The survey was conducted March 13 and 14.

Some findings are based on 176 schools that reported receiving information from their preferred lenders for the 2008-09 school year.

Among those schools:

• 46 percent heard from at least one lender intent on stiffening credit standards.

• 43 percent heard from at least one lender that will no longer provide non-federally-guaranteed loans.

• 30 percent said one or more lenders are cutting or eliminating borrower benefits, which typically have included better interest rates and payment of origination or default management fees.

Of the 211 responding schools that received information from private lenders in the FFELP program, 57 percent of the schools said one or more lenders have stopped providing FFELP loans.

A student unable to secure a loan might have to consider a less expensive school or suspend studies, said Maureen Budetti, the association's director of student aid policy.