The Scottish Government is unlikely to meet its target for building affordable homes on current spending levels, the body which represents housing associations has warned.
Ministers have pledged to build 30,000 affordable homes during the lifetime of this parliament.
In his recent budget for 2013-14, Finance Secretary John Swinney announced an "immediate stimulus" of more than £40 million for this, with the cash being spent this autumn and in the coming financial year.
But the Scottish Federation of Housing Associations (SFHA) said: "The programmed expenditure on new affordable housing supply is unlikely to meet the Scottish Government's objective to build 30,000 homes for social rent and other tenures."
In a submission to MSPs on Holyrood's Infrastructure and Capital Investment Committee it said that "many" housing associations warned that they may be "unable to develop new supply at the lower grant rates".
It "remains difficult to deliver genuinely affordable, high-quality social rented housing at these subsidy benchmarks". It wants a higher subsidy for affordable homes, along with additional resources to "ensure that the people of Scotland all have access to a safe, warm and affordable home".
While the SNP administration has committed to build 30,000 such homes between 2011 and 2016, the SFHA said: "To put the scale of the shortage in perspective, there are 335,000 households on waiting lists in Scotland." The committee is due to hear from the SFHA as part of its scrutiny of the Scottish budget.
Also giving evidence will be the body which represents council housing chiefs, the Association of Local Authority Chief Housing Officers. It said that "councils seem confident that the financial capacity exists to deliver on the Government's targets".
Planned expenditure levels are "likely to be sufficient to meet current government output targets". But it said: "Most councils would say the current output of social housing does not come close to meeting the absolute needs identified in local housing strategies. For this to occur would require a significant addition to the national affordable housing budget, and quite possibly upward movement in grant levels."
A Scottish Government spokesman said that 6,882 affordable homes were built in 2011-12, "far in excess of our target of 6,000 affordable completions each year".