Over a third of London homes flogged on the cheap under Thatcher's right to buy scheme have fallen into the hands of private landlords, a London Assembly Member revealed yesterday.

Labour AM Tom Copley revealed that 52,000 former council properties are now being let at inflated prices - driving up Britain's housing benefits bill.

He described the Tory sell-off as a "Whitehall-sanctioned robbery of the taxpayer" which has left councils with huge housing waiting lists.

His report shows local authorities have been forced to rent homes which they previously owned at soaring market rates to keep families off the streets.

The average housing benefit claim from private tenants in some boroughs has reached £5,200 a year - £100 per week more claimed than council tenants.

And yet the research shows complaints against private landlords have risen by 47 per cent since 2008 and the physical state of private rented homes is worse than other homes.

Mr Copley said: "This shows that right to buy currently represents incredibly poor value for money to taxpayers.

"Not only did they pay to build the home in the first place, they then subsidised the considerable discounts offered to tenants and then missed out on the rental income that would have covered the build costs.

"Now, we have the indignity of London boroughs renting back their former council homes at higher market rent levels, once again costing taxpayers through the nose."

The London Assembly Labour group's housing spokesman called for a ban on discount sales of council homes to help stop the city's housing crisis.

Mr Copley also called for the replacement of council homes sold under Thatcher's policy, which "mirror the rent, size and tenure" of those sold.

"Right to buy has played a central role in causing and exacerbating the current housing crisis," he added.

"Future governments must recognise that the right of a council tenant to buy their home at a discount, subsidised by other taxpayers, cannot be at the expense of the right of the vast majority of people to have a decent, affordable home to live in."

Shadow housing minister Emma Reynolds pledged Labour would begin a council house-building programme if it wins the next general election.

Labour leader Ed Miliband has previously promised a government led by him would build 200,000 new homes a year and Ms Reynolds will unveil details in a speech today.