RBS has been accused of using diversionary tactics by Lawrence Tomlinson, an adviser to Vince Cable, after a report into accusations of malpractice by the bank.

Tomlinson told the Sunday Herald the substance of the RBS report, conducted by lawyers Clifford Chance, corroborates many of his findings about the bank's Global Restructuring Group (GRG), which is accused of deliberately undermining viable client companies.

He took issue with the bank's claim it had been "cleared of fraud", which it said was Tomlinson's "central allegation" in his report to the Business Secretary last November. The entrepreneur said he had never accused RBS of fraud, a word not mentioned in his original report.

He said RBS was diverting attention away from the substance of the report: "That seems to be a deliberate misdirection from Clifford Chance's real findings."

Tomlinson, whose one-year stint as entrepreneur-in-residence at the Department for Business ended on April 6, is chairman of Leeds-based LNT Group.

He said Clifford Chance's findings about the lack of fee transparency, lack of adherence to mandatory rules for internal valuations, and the need to improve the business culture of GRG, essentially endorsed his own.

He also welcomed the bank's ­decision to close West Register, its controversial property unit; its waiving of default interest for 90 days; and its introduction of more transparency over fees and charges to distressed firms.

Tomlinson said these moves cut the bank's incentive to transfer viable firms into the GRG, a business support unit some customers said was "more like an abattoir than a high-dependency ward".

He said: "The Clifford Chance report does not exonerate RBS. The law firm admits it was unable to work out how RBS calculates the fees charged to customers in GRG."

Clifford Chance alleges RBS failed to abide by the Royal Institute of Chartered Surveyors' best practice in valuing customers' commercial property, saying: "Internal valuations were not carried out to the standard of the Red Book."

However, the lawyers say they saw no evidence RBS pressured surveyors to manipulate valuations to trigger breaches of covenant by customers, even though such claims have been backed in an opinion of Lord Malcolm in the Court of Session (O'Donnell and McDonald vs RBS, May 28, 2013).

Alison Loveday of Manchester-based solicitors Berg said the bank changed policy on commercial property in 2008, shifting from three-yearly valuations from reputable surveyors to "back-of-a-fag-packet internal valuations".

She said these had the advantage for the bank of being easier to manipulate to its own ends. In its report, Clifford Chance said: "In our review we did not test the accuracy of the bank's valuation methodology."

The lawyers' report confirmed RBS staff threatened to withdraw overdrafts to cajole business into actions that would deliver "upsides" for the bank, such as equity stakes in customer firms or the payment of higher fees.

It also stated: "We observed, in a GRG training manual … a reference to using the on-demand nature of the overdraft as a point of leverage in negotiations." It suggested the bank may wish to "revisit" the manual.

On the percentage of firms that entered GRG and came out as going concerns, Clifford Chance admitted the so-called "return to satisfactory" figures do not disprove what it calls Tomlinson's central allegation.

The report also confirmed some viable firms not in default were transferred to GRG. Tomlinson claimed this happened in some cases because the bank wanted some of their assets and hoped to get them after hobbling the firm with extra fees and charges. It confirmed GRG managers are incentivised to deliver a higher "financial contribution", and that staff appraisals focus almost exclusively on "revenue generation/loss avoidance".

As well as failing to examine GRG's charging structures, Clifford Chance did not look at anything said in phone calls or meetings. Critics say this stopped it fully probing alleged wrongdoing, as things such as alleged verbal threats made by GRG staff to customers were not taken into account.

Neil Mitchell, former chief executive of Torex Retail and chairman of the RBS GRG Business Action Group, said: "This report will not wash. Now it is published we can get on with the further exposures and actions planned on behalf of the over-2000 cases. There's no doubt that this is a serious matter best judged by the regulatory and criminal investigative authorities and in court."