Families earning more than £100,000 and people moving up the housing ladder are among those taking advantage of a government scheme which is offering a "blank cheque" to builders, Labour has claimed.
The scheme, which offers loans guaranteed by the state for up to 20% of a property's value - or 40% in London - was launched in 2013, allowing Brits to get on the property ladder with as little as a 5% deposit.
But shadow housing minister John Healey said the programme was poorly targeted and called for a cap on the total income of households eligible to take part.
More than 90,000 first time buyers have been helped onto the property ladder by the initiative, but figures show that more than 20,000 were people moving up the housing ladder.
In addition, some 3,952 households in England earning more than £100,000 annually have bought a home using the Help To Buy Equity Loan scheme, out of a total of 112,338 completions.
The government offers the equity loan to buyers of newly-built properties worth up to £600,000.
Mr Healey told BBC Radio 4's Today programme: "I don't think it's right that taxpayers' help is going to people who are earning over £100,000, many of whom say they could have afforded to buy that without that help.
"A lot of this help is not even going to people who are buying for the first time. So ministers have got to do a great deal more to target this scheme on help for those with ordinary incomes, younger people who really need the help most."
Mr Healey added that the scheme should be limited to people getting on the housing ladder for the first time and there should be ban on people with "sky-high incomes" from getting the support - although he refused to put a figure on where the cap should be set.
However housing expert Henry Pryor urged caution on criticism that the scheme has been poorly targeted.
Speaking to ITV News, he said: "We have to remember that these are household incomes not necessarily individuals, so two people living in London earning £50,000 each would actually only be able to get a mortgage probably of around £400,000 and the Help To Buy Scheme is designed to enable people onto the housing ladder up to £600,000 so inevitably there will be some people who by and large are considered not necessarily to be the people most in need."
"We have to remember why the scheme was brought in in the first place," he said. "The government were keen to try and encourage lenders to get back out and lend money to those who wanted to buy homes. Lenders in turn were very concerned about lending money on what might be a depreciating asset.
"As a result, the government's assistance to try and protect or insulate lenders made a significant difference. The big question is now whether it's past its best before date and there are many people, myself included, who would consider that Help To Buy perhaps now has become Help To Build and perhaps its time has come and gone."
A Department for Communities and Local Government spokesman said: "Since 2010, Government-backed schemes have helped more than 362,000 households to buy a home, with the number of first-time buyers more than doubling since 2009.
"We have been clear that we need to fix the broken housing market so that homes are more affordable and people have the security they need to plan for the future - and our recent housing white paper set out the measures to do just that."