The Financial Conduct Authority (FCA) said in a letter to Amigo that it was concerned customers' compensation claims would be significantly reduced while shareholders were not being asked to contribute, the company said.
Amigo said over 95% of votes cast by current and former customers to date were in favour of the scheme, ahead of a creditors' meeting on Wednesday. The scheme requires 50% creditor support and at least 75% of the value of claims.
Amigo's rescue plan has drawn criticism from politicians and consumer groups for potentially short-changing customers.
(Reporting by Muvija M in Bengaluru, Editing by Iain Withers)