The Law Society of Scotland said the system was in need of “urgent overhaul” following the publication of research carried out on its behalf.
The report, The Financial Health of Legal Aid Firms in Scotland, warned that some of the country’s smallest legal aid law firms are carrying out the work at a loss and are at serious risk of being unable to offer legal aid services.
But the Scottish Legal Aid Board said it had “very serious concerns” about how the research was conducted.
Eilidh Wiseman, president of the Law Society, said: “We are deeply concerned that people relying on legal aid to help them, whether facing unlawful eviction, resolving custody of their children, or defending a criminal charge, may soon be unable to find a legal aid solicitor because sadly many solicitors simply can’t afford to carry out this work.
“Every person in Scotland should be able to access the legal advice they need and have equal protection under the law, regardless of financial situation or status in society. The Scottish legal aid system needs an urgent overhaul.”
Nearly £140 million was spent on legal aid in 2015-16, the majority going on criminal legal assistance.
Earlier this month the Scottish Government announced an independent review of legal aid led by Carnegie Trust chairman Martyn Evans.
A spokesman for the Scottish Legal Aid Board said: “We share the Law Society’s strong interest in the financial health of legal aid firms in Scotland, which on the basis of its report appears to be fairly robust. The society’s report shows that the majority of firms participating in its survey are profitable and those doing more legal aid work are substantially more so.
“However, we have a number of very serious concerns about the analysis. We have already pointed out major errors, some of which the society has corrected, but the report still presents an inaccurate and misleading picture.”
A Scottish Government spokesman said: “The independent review is taking a long-term and strategic look at the legal aid system. We want to focus legal aid on those who need it most and have maintained access to publicly funded legal aid in both civil and criminal cases.
“The independent review is about ensuring there is a flexible and progressive system that is sustainable.”