Vital home care services for the elderly could be disrupted in many parts of England, regulators say.
The Care Quality Commission has issued a notice saying it has serious doubts about the future of Allied Healthcare.
The CQC said it was concerned about its prospects from the end of this month, but the firm said the move was “premature and unwarranted”.
The company provides services, such as help washing and dressing, to around 9,300 people across 84 council areas.
Allied Healthcare announced earlier this year it was struggling with debts, but was in the process of restructuring its finances.
The CQC said the company had only be able to confirm it had funding in place until 30 November.
The regulator said it had a legal duty to warn councils that business failure was likely and services could stop as a result in its view.
This is the first time a notice like this has been issued to a provider.