In the Woolwich Mortgage Affordability study conducted by Barclays about a third of first-time buyers'income is now spent making payments on secured loans. Over the course of June, those homeowners in their 20s - reported to make up the majority of first-time buyers - use 32.4 per cent of their annual salaries on their mortgage. However, across borrowers of all groups mortgage payments were reported to account for 20.1 per cent of income, the highest level recorded since 2002.

Andy Gray, head of mortgages for the Woolwich, said: "For those in their 20s not already on the property ladder the outlook for getting on it doesn't look good, especially with interest rates likely to rise further. We fully expect the average age of first-time buyers to go up until people are well into their 30s." Mr Gray suggested that as potential first-time buyers struggle more to meet the rising costs of property deposits and secured loans, the average age of those getting on the first step of the housing ladder is set to rise past the current median of 29.

Figures from the financial services firm also indicated that those in their 20s paid an average of 586 pounds towards their secured loan last month, a 66 per cent rise from the average 233 pounds spent five years ago. Those living in London were reported to have the greatest proportion of their pay taken up by mortgage costs as they shell out an average of 830 pounds, just over 40 per cent of their monthly wage. However in some parts of the capital this figure was found to approach the 50 per cent barrier. Some of the other most expensive areas around the country include Cambridge, Oxford and Brighton.

Meanwhile, the north-east of England was said to be the region with the lowest monthly mortgage costs at 470 pounds - equating to some 28.3 per cent of salaries. A low proportion was also noted in the Staffordshire Moorlands as those living in the West Midlands district are reported to put 18.9 per cent of their income (301 pounds) towards secured loans.

However, Mr Gray added that an increase to the interest rate could lead to further problems for first-time buyers. "The last thing any of them need is a further increase in base rates," he added.

According to statistics published by Moneyfacts, should the Bank of Englands' monetary policy committee decided to increase the base rate by 0.25 per cent, those on a 150,000 pounds repayment mortgage could find their monthly costs jump to 943 pounds 66p - a rise of 22 pounds 53p. However, homeowners on an interest-only mortgage are set to see payments increase by 31 pounds 25p to 718 pounds 75p.

Consequently, managing director of moneysupermarket, Stuart Glendinning advised those concerned about the effect a base rate rise may have to review their "situation rationally as there are several logical steps that can be taken to alleviate financial distress". He suggested that consumers should look to pay off debts on "expensive" unsecured loans and seek professional advice, with remortgaging another possible option.