First-time buyers who still have student loans to pay off could be heavily disadvantaged by the new mortgage rules.

Among those affected will not only be recent graduates, but those who may have graduated ten years ago – none of whom would have been advised of the implications that have now emerged.

They could find their mortgage applications rejected outright or the amount they want to borrow slashed.

Although student loans are commonly perceived as not being a problem for credit rating purposes, the Financial Conduct Authority and the Building Societies Association have both confirmed they will be taken into consideration by lenders following the Mortgage Market Review.

The BSA said they would be included as part of the affordability assessment: “We would urge all borrowers with student loans to be responsible and realistic and reduce their debt elsewhere as much as possible if they are thinking of applying for a mortgage.”

Alexander Burgess, director of finance firm British Money, said: “There appears to be a common misconception among students that anyone who has taken out student finance will have their loan discounted, but this simply isn’t the case.

“Universities imply it’s not considered to be a debt, credit rating firms are swerving the subject on whether they’ll access student loans records, and financial sites such as Money Saving Expert suggest ‘student loans do not go on credit files’.”

Halifax also confirmed that as a lender it is now looking at student debts when it considers mortgage applications, while brokers London & Country Mortgages said: “Any kind of loan payment will be factored into an affordability calculation as a commitment and it will have a direct bearing on how much the applicant can borrow.

“Any regular cost, including a student loan, will therefore potentially reduce the level of mortgage borrowing.”