Unpaid credit card debt is on the rise, according to a Associated Press analysis of financial data from the country’s largest card insurers.

According to the report, delinquencies and defaults surged by double-digit percentages in the last year, which has many market watchers wondering if the worse is still to come. The greatest rise, the report found, was among accounts more than 90 days overdue.

Some experts believe the deterioration of finances is partly due to the subprime mortgage crisis.

The value of credit card accounts at least 30 days late jumped 26 percent to $17.3 billion in October from a year earlier at 17 large credit card trusts examined by the AP. That represented more than 4 percent of the total outstanding principal balances owned to the trusts on credit cards that were issued by banks such as Bank of America and Capital One, and retailers like Home Depot and Wal-Mart.

Defaults rose 18 percent to almost $961 million in October, according to filings made by the trusts with the Securities and Exchange Commission. Serious delinquencies are also up sharply, with some of the nation’s biggest lenders reporting increases of 50 percent more in the value of accounts that were at least 90 days delinquent when compared to the same period a year ago.