Housing campaigners have warned that ministers' right-to-buy policy may cause them to miss their target to end homelessness.
The SFHA said homeless targets may be missed
The Scottish Executive's long-term goal is to provide permanent homes for all homeless people by 2012.
The Scottish Federation of Housing Associations (SFHA) criticised a shortage of affordable homes and demanded a freeze on right-to-buy.
The executive said the policy would be evaluated next year.
Jackie Watt, from the SFHA, said: "The Scottish Executive is struggling to meet its commitment to house all homeless people by 2012, yet right-to-buy is draining houses out of the system.
"It will fail to meet that target unless we can protect the housing stock that exists."
Council house sales in parts of the Highlands were suspended last month to protect affordable stock.
The executive agreed to the local authority's five-year move to ease pressure on the market.
Ministers estimated that the ban - welcomed by Shelter Scotland - would cover about 2,000 tenants and halt the potential sale of 570 properties.
East Renfrewshire Council was the first in Scotland to be given permission to ban council house sales.
A spokesman for the executive said: "Legislation commits us to report on the effect of the right-to-buy by September 2006.
"We will consider the merits of the cases being made for further adjustments to the right-to-buy in the light of the report."