David Cameron was questioned by Ann McKechin, Labour MP for Glasgow North, in Parliament over fears foreign buyers could take advantage of the scheme, rather than first-time buyers as intended.

She told Cameron that the Treasury had failed to give a direct answer on the issue and asked: “Will British taxpayer’s money be used to guarantee the mortgages of foreign citizens who buy property here?”

The Prime Minister said he would not comment until Chancellor George Osborne released further details of the scheme.

“The Chancellor will set out details of this in the announcements he plans to make,” he said.

Figures released today show the equity loan aspect of the Help to Buy scheme has generated over 4,000 reservations for new homes since its launch in April but questions remain over whether the mortgage guarantee, which launches in January, will allow foreign buyers to purchase properties in the UK with government support.

McKechin later told the Daily Mail: “I have serious concerns about these proposals and believe they will not assist the property market for ordinary people.

“I find it simply astonishing that over two months since the schemes were announced, the government is still incapable of answering straightforward questions as to how they will operate and how they will benefit UK taxpayers.

“Even worse, the government cannot rule out the possibility that UK taxpayers will be underwriting a property bubble generated by foreign buyers with considerable risks to public spending – it is a mad scheme which is now simply unravelling before our eyes.”