A spokesperson for EY said the delivery of high-quality audits remained its "absolute priority" and it was investing in technology and processes to drive continuous improvement.
Oliver Clive & Co did not immediately respond to a request for comment.
UK taxpayers have paid about 120 million pounds to compensate investors in LCF, which sold complex bonds to thousands of retail investors before lending the proceeds to commercial clients.
The company was regulated by the Financial Conduct Authority prior to its demise.
"These breaches are made considerably more serious by the fact that all of the auditors knew they were auditing an expanding business which was engaged in selling unregulated financial products to retail investors, and that potential investors might place reliance on the clean audit opinions," Jamie Symington, the FRC’s Deputy Executive Counsel, said of all three audits.
