The U.S. Postal Service says it lost $2 billion this spring despite increasing its volume and charging consumers more money to send mail.

The agency's quarterly loss was significantly higher than its $740 million loss during the same three-month period last year. The agency said revenue jumped 2 percent compared to last year. But because of compensation and benefit costs, the agency continues to face a deficit.

Agency officials said the Postal Service would likely remain in bad shape unless Congress acts on reform legislation. In a statement released Monday, the agency said it would have to default on a congressionally mandated payment of $5.7 billion this September for health benefits for future retirees.