Britain's bailiffs are chasing 70 per cent more debt than two years ago, according to a study published on Tuesday.

The average household now owes £25,000 spread across 15 different lenders, the Leeds University Business School found, compared to £10,000 three years ago.

The rise in debt has been almost entirely blamed on an increase in the number of people falling behind on credit card and personal loan repayments.

In addition, the Credit Services Association has reported a surge in the numbers declaring bankruptcy, particularly in Scotland.

Critics have blamed aggressive marketing techniques behind the 1,500 different credit cards now on offer.

"It is clear to me the aggressive promotion of debt is behind this rise," said Liberal Democrat Treasury spokesman Vincent Cable.

"Unsolicited mailshots advertising credit should come with a health warning much like cigarettes, saying: 'This product can seriously damage your wealth.'"

The use of bailiffs by local councils and utility companies on "the slimmest of pretexts" featured heavily in letters to MPs, a view confirmed by researchers at the Leeds University Business School.

"The emphasis in recent years has switched to being more aggressive in dealing with early delinquency," said the study.

"Customers are contacted earlier and more frequently in very early stage delinquency and late payment charges are threatened and imposed."

It also pointed to an increasing trend of lenders selling the names of those owing money to external agencies, for as little as one per cent of their total value.

These agencies keep any cash they can extract from borrowers, making a profit if they can obtain one pence in the pound from the worst-offending borrowers.

The report comes ahead of a consumer credit white paper to be published by the Department of Trade and Industry, which will propose that the 1974 Consumer Credit Act - which governs loans below £25,000 - should be overhauled.

"The report makes clear what has become already very apparent, that the dependence of the chancellor to have an economy which is propped by consumer spending is encouraging extended credit lines," said shadow Treasury minister Stephen O'Brien.

"Whilst it is just too simple and populist to talk of cracking down on loan sharks - they have always been around and should always be avoided - the government has to take this report very seriously in an age of consumerism when people want to have things sooner than they have earned the money to pay for them."

The Treasury select committee is also looking into the matter, with the chief executives of five major banks giving evidence on Thursday.

"The committee has been looking at this issue of increasing debt and responsible lending and from this report it's clear the problem is deeper and wider than has previously been acknowledged," committee chairman John McFall told ePolitix.com.

"The key to transforming this situation is consumer education and increased transparency for the consumer, and practices such as unsolicited increase in credit limits and lack of information on minimum repayments timescales only assist those with multiple credit cards to tiptoe into disaster.

"So we will be focusing on these issues of consumer education and transparency in order to minimise the practices of irresponsible lending and irresponsible borrowing."