The Government's right-to-buy scheme will lead to 75,000 fewer low cost houses becoming available over the next five years, according to a new study.
The Joseph Rowntree Foundation said there will be a reduction in the number of low cost homes able to be let if houses built to replace them are sold as shared ownership.
Building replacement houses as shared ownership will mean that people looking for a social rented home will be pushed to the bottom end of the private rented sector, said the report.
Houses in the private rented sector are typically more expensive and in worse condition than Housing Association homes, said the report.
Julia Unwin, chief executive of the Joseph Rowntree Foundation said: "To get to grips with the housing crisis we desperately need more affordable homes across all tenures, and right to buy will help unlock home ownership for some families who would not otherwise have been able to afford it.
"But this research shows how important it is to keep up the numbers of genuinely affordable rented homes. To make sure that this policy doesn't drive up poverty in the long term, the Government must ensure that every low-rent home sold is replaced by another of the same tenure, same cost and same locality."
Anna Clarke of Cambridge University's Centre for Housing and Planning Research, which wrote the report, added: "Replacement homes for sale or shared ownership will not be affordable to those seeking social rented housing.
"Replacement on a like-for-like basis could have a positive impact on the availability of social lettings, over the next five to 10 years, though in the long term the subsidy for right to buy discounts cannot forever be found by selling off high value council stock without continually stretching the definition of high value."
JRF is calling for MPs and peers to amend the Housing and Planning Bill so that all homes sold in connection with this policy are replaced on a like-for-like basis with a home of the same tenure, cost, and locality.
Some Welsh councils have suspend the right to buy scheme in a bid to cope with a shortage of social housing.