Another ad on that Web site is directed at military veterans: “You’ve put your life on the line for Americans to protect our way of life. You deserve to do something important for yourself.”

A review by The New York Times of more than two dozen contracts for pension-based loans found that after factoring in various fees, the effective interest rates ranged from 27 percent to 106 percent — information not disclosed in the ads or in the contracts themselves. Furthermore, to qualify for one of the loans, borrowers are sometimes required to take out a life insurance policy that names the lender as the sole beneficiary.

LumpSum Pension Advance and Pension Funding did not return calls and e-mails for comment.

While it is difficult to say precisely how many financially struggling people have taken out pension loans, legal aid offices in Arizona, California, Florida and New York say they have recently encountered a surge in complaints from retirees who have run into trouble with the loans.

Ronald E. Govan, a Marine Corps veteran in Snellville, Ga., paid an interest rate of more than 36 percent on a pension-based loan. He said he was enraged that veterans were being targeted by the firm, Pensions, Annuities & Settlements, which did not return calls for comment.

“I served for this country,” said Mr. Govan, a Vietnam veteran, “and this is what I get in return.”

The allure of borrowing against pensions underscores an abrupt reversal in the financial fortunes of many retirees in recent years, as well as the efforts by a number of financial firms, including payday lenders and debt collectors, to market directly to them.