The total amount owed by consumers through mortgages, loans and credit cards rose by 7.3 per cent during the year to the end of June to stand at £1.444 trillion, according to accountants Grant Thornton.

But during the same period gross domestic product (GDP) rose by only 5.1 per cent in nominal terms to £1.41 trillion.

As a result it would take until January 8, 2009, to pay off the UK's outstanding consumer debt from GDP during a calendar year.

The date at which GDP can cover consumer debt has been getting later and later during the past decade, after falling on August 23 in 2007 when personal debt amounted to just £503bn and GDP was £786bn.

The group said the figures showed that despite tighter lending criteria and a reduced availability of debt as a result of the credit crunch, the UK was continuing to be affected by the legacy of cheap borrowing over the past few years.

Stephen Gifford, Grant Thornton's chief economist, said: "Despite the global downturn flattening the growth of personal debt and UK GDP over the past few quarters, debt levels continue to grow at a faster rate than the income the UK generates.

"Although there is no cause for panic as personal debt is well covered by the UK housing stock, the figures clearly illustrate the continuing problem of growing personal debt levels in the UK.

"If the property market and economy continue to weaken, the current levels of personal debt will become unsustainable and there will be a marked increase in personal insolvencies."

But he added that the UK economy had benefited from the high levels of personal debt, as economic growth had been driven by consumer spending.

During the past 10 years, the number of people declared insolvent has risen from an average of 24,000 a year in 1997 to more than 100,000 a year in both 2006 and 2007.

The latest figures show that 49,607 people have been declared insolvent during the first six months of this year, and Grant Thorton is predicting the total number for 2008 could be more than 100,000 and close to 120,000.

It said the full impact of the credit crunch was likely to begin to show in the figures during the next six to 12 months, with personal insolvencies rising sharply in the fourth quarter of this year and early in 2009.

One in 20 Britons has had a credit application turned down during the past 18 months as lenders tighten their lending criteria in the face of the credit crunch, a survey showed.

Around five per cent of people said they had had a mortgage or loan application refused since the beginning of 2007, with 13 per cent of these saying they made at least four applications before they were successful.

A further one per cent of people who were rejected had to apply for a mortgage or loan at least eight times before they were accepted, according to GE Money Home Lending.

The group said the trend among lenders to tighten their lending criteria in the face of the credit crunch was leading to previously creditworthy people being classed as a higher credit risk.

It said as a result of this trend, many consumers were finding it more difficult to secure the credit they needed.

Nearly a third of people who had a credit application turned down said they gave up applying after being rejected, while 12 per cent said they had not been accepted by any lender despite making repeated applications.

GE Money Home Lending warned people that making multiple credit applications could increase their risk of being turned down, as failed applications could be logged on people's credit records and count against them.

Gerry Bell, head of mortgage marketing at GE Money Home Lending, said: "Multiple failed applications can be time consuming and, of course, can be detrimental to a borrower.

"With criteria changing regularly and the risk of decline increasing all the time, it is even more important that borrowers looking to obtain a mortgage use reputable mortgage professionals with broad experience, knowledge and systems at their disposal which will increase the chances of the borrower getting the deal they need."