Student-loan defaults surged in the first three months of 2013, while efforts to collect bad loans are faltering, according to credit analysts and government audits. It is the latest twist in a college debt crisis that is hanging over recent graduates and dragging on the broader economy.

Credit-rating firm Equifax said $3.5 billion in government and private student loans went bad in the first three months of 2013, the most since the company began keeping track. The U.S. Department of Education said 6.8 million federal student loan borrowers are now in default, representing $85 billion in debt. And the department's systems for collecting the bad loans are struggling to keep up.