Jim McColl, one Scotland's highest-profile business figures, has added his weight to a growing backlash against the Financial Services Authority's perceived attempt to blame the collapse of HBOS on the bank's former head of corporate lending, Peter Cummings.

McColl, chairman and chief executive of Clyde Blowers Capital, described the FSA's investigation of HBOS as "an absolute disgrace" and accused the regulator of structuring it in such a way that it ignored the roles of "establishment" figures such as former HBOS chairman Lord Stevenson and chief executive Sir James Crosby.

Between 2004 and 2009, Crosby was also a director and deputy chairman of the FSA.

The FSA on Wednesday published a "final notice" accusing Cummings, 57, of failing "to take reasonable steps to assess, manage or mitigate the risks involved in the aggressive growth strategy which the corporate division, under his direction, was pursuing". In the most severe penalty handed out since the crisis began, the former "banker to the stars" was fined £500,000 and banned from working in financial roles for life.

However, even critics of Cummings have attacked the FSA for appearing to ignore the roles of other former HBOS directors – including Crosby, Stevenson and Andy Hornby – in the bank's collapse, and for omitting to question either of HBOS's former finance directors, Phil Hodkinson or Mike Ellis.

Crosby and Stevenson are known to have actively encouraged Cummings to lend more riskily to corporate borrowers, even after the credit crisis commenced in July 2007, in order to compensate for a downturn in retail lending.

The FSA report confirms allegations made in a new book by former Scottish Financial Enterprise chief executive Ray Perman – Hubris: How HBOS Wrecked The Best Bank In Britain – which details how Hornby and the HBOS management team put "heavy pressure on [Cummings's] corporate [banking division] to make up the slack" when mortgage and credit-card lending became less profitable.

McColl, one of Scotland's most successful entrepreneurs, and a recent convert to Scottish independence, told the Sunday Herald: "Crosby and Stevenson are establishment insiders. They have a lot to answer for.

"I think it is an absolute disgrace, and the Government or the Treasury Select Committee should do something about it. [The system] is so incestuous you cannot get a proper result, and that's why a lot people don't speak out."

The entrepreneur, whose takeover of Weir pumps in 2007 was financed by HBOS, added: "The way that the FSA has singled out Peter is disgraceful. There was a whole board overseeing it. It is ludicrous to say he was acting alone."

Paul Moore, the former head of group regulatory risk at HBOS-turned- whistleblower, is a strong critic of Cummings's strategy and methods. He said: "The FSA final notice is a spiteful attempt to draw fire away from the really big players, including Hornby, Crosby and Stevenson, onto someone who the regulator believes can be used as a fall guy.

"Cummings was not a rogue trader. He could not have done what he did without the authority of a whole superstructure of risk committees, audit committees and the board itself.

"Everybody within that structure was fully aware of the levels of risk that were being taken on."

On Friday, the Treasury Select Committee told the FSA it would appoint independent advisers to oversee the regulator's final report into the HBOS debacle, with parallels to the work undertaken by Sir David Walker and Bill Knight on the RBS report.

The committee's chairman, Andrew Tyrie, said the committee would require the FSA to conduct a "comprehensive assessment" of the reasons for HBOS's collapse and of the FSA's conduct in relation to the bank.

In a further development, entrepreneur Sir Tom Hunter, also a former client of Cummings, stepped up his criticism of the ruling last night, saying: "How can the FSA, who are 100% conflicted, conduct a review objectively when they were complicit in HBOS's failure? Parliament should instruct an independent review. The FSA acts as judge, jury and executioner and that cannot possibly be fair."

Having built up a toxic £119 billion corporate loan book, Cummings "retired" from the bank he helped destroy with a £352,000-a-year pension in January 2009. He now works part-time as a consultant and lives in Dumbarton.

Crosby stepped down as HBOS's chief executive in July 2006 and was forced to resign as FSA deputy chairman in February 2009. He remains a non- executive director of Misys and Compass Group, and a member of the European advisory board of private equity group, Bridgepoint.

Stevenson walked away from the HBOS wreckage after it was rescued by Lloyds TSB in January 2009. He is a non-executive director of bookseller Waterstones and venture capitalist, Loudwater.