US consumers are defaulting on credit-card payments at a significantly higher rate than last year, raising the prospect of problems in the stricken US subprime mortgage market spreading to other types of consumer debt.

Credit-card companies were forced to write off 4.58 per cent of payments as uncollectable in the first half of 2007, almost 30 per cent higher year-on-year. Late payments also rose, and the quarterly payment rate – a measure of cardholders’ willingness and ability to repay their debt – fell for the first time in more than four years.