"The government's Help to Buy scheme is very much a work in progress, " said the committee's chairman, Tory MP Andrew Tyrie.

BBC: George Osborne warned by MPs over mortgage guarantee risks

"The maths suggest that the chancellor has 110, 000 shared equity homes in his sights under the Help to Buy scheme" said Frank Nash, from Chartered Accountants Blick Rothenberg.

BBC: Budget 2013: Chancellor extends home-buying schemes

As the government sought to clarify the situation, Housing Minister Mark Prisk denied suggestions by Labour shadow chancellor Ed Balls that the Help to Buy scheme was potentially a second-home "subsidy".

BBC: Budget 2013: Row over 'second home subsidy'