An investigation conducted by the BBC has unearthed evidence that borrowers have been told to lie about their wages on self-certification products - despite current industry regulation.
The report claims that intermediaries push homeowners to take out bigger loans than they can afford to pay back, leaving them in serious financial trouble.
One borrower interviewed in the programme said that even though his real income was £25,000 he was advised to double it when it came to filling in his mortgage application – leading to a final loan of more than eight times his salary.
His monthly re-payments take up most of the family's income and he has been threatened with re-possession.
The BBC said that it is impossible to tell how many other cases like this there are because few borrowers or mortgage brokers will admit to the practice. However it states that campaigners have urged the Financial Services Authority (FSA) to take action against those involved.
Alan Lakey, senior partner at Highclere Financial Services, believes it is difficult to know to what extent this permeates the market: "People who cut corners and exaggerate just because they can get away with it is a fundamental problem in any market. One has to be far more cautious and make a valued judgement."
"However It is important to look at this is a wider light; these types of programme tend to prove that the bad apples do indeed exist, and if you go looking then you will undoubtedly find them."
The programme will air tonight at 8pm on BBC File On 4.
