David Cameron’s new Starter Homes initiative could fail through lack of support from mortgage lenders, it has been claimed.

The scheme will allow first-time buyers under the age of 40 to buy a new home at a discount of 20%, with online registrations invited now for 200,000 homes.

These would be built on brownfield or ‘other’ sites, with the discount being made possible by the normal contributions developers make to local councils being waived.

The ‘other’ sites could be allocated for Starter Homes as part of larger housing schemes. The Tories have confirmed that Starter Homes could replace the affordable homes requirement.

However, a key part of the Starter Homes plan is that should buyers sell within five years, they would have to repay the 20% concession – an average of £43,000.

According to Andrew Frankish, new homes director at the Mortgage Advice Bureau, this would deter lenders.

He said: “Crucially, there has been no mention of maximum loan-to-values: for this scheme to be successful or even to compete with Help to Buy, 95% mortgage lending must be available.

“However, many lenders could be put off from offering this if they are not able to sell at full market value for five years, which is problematic in a repossession scenario.

“The general lack of lender and broker involvement in the early stages of this scheme could also prevent it from having a flying start: little is known about its mechanics so it may be a while before widespread lender support is obtained.

“Without a good lender mix, the scheme could quickly lose momentum, and if the sites are all brownfield developments surveyors will need to be certain property will hold value.

Frankish said the number of first-time buyers the government aimed to support with the Starter Homes scheme was “a drop in the ocean compared to the current housing crisis”.

Other critics of the Starter Homes initiative to have expressed their doubts include the British Property Federation, which said it was sceptical as to whether the scheme could deliver the number of homes promised.

It said most developers would prefer to develop brownfield sites to sell at full market price.