The average adult now owes £33,000 through mortgages, credit cards and personal loans compared with £17,000 in 2000, the international accountancy firm PricewaterhouseCoopers claims.

As borrowers default on their debts in growing numbers and banks and building societies try to recoup their losses, annual fees on credit cards will become standard, the report says. These would equate to up to £30 a year.

Despite the prospect of annual charges and higher interest rates on monthly bills, many people are likely to have to use their credit cards more often to meet the rising cost of mortgage repayments.

The report comes as families prepare for Christmas, when the average adult takes on more debt than at any other time of the year.

Further pressure will be applied this year when more than a million people see their discounted fixed-rate mortgage deals end, the report predicts. They face an average rise of £140 on their monthly repayments.

The report delivers a bleak warning about the level of consumer borrowing in Britain, which now stands at more than £1.3 trillion.