Small businesses have shed thousands of jobs under pressure from the liabilities built into Clydesdale and Yorkshire bank 'tailored business loans' (TBLs), an action group has claimed.

The NAB Customer Support Group said its 53 SME members had reported job losses totalling 367 "as a direct result of our members' adoption of long term fixed rates in TBLs".

It said those businesses' loans totalled £88 million, a fraction of the £5.6 billion commercial real estate portfolio transferred from Clydesdale and Yorkshire banks to parent National Australia Bank last year.

This implied that more than 23,000 jobs might have been lost to the economy in firms holding TBLs, the group claimed.

John Glare, spokesman for the group, said: "These are the jobs lost directly by the SMEs and do not include those lost indirectly, for example, by other com­panies supplying our members or through lost tax revenues."

Bank mis-selling of unsuitable hedging products to small businesses has cost the UK economy more than 400,000 jobs and £1.7bn of lost taxes, creating a hidden brake on economic recovery, according to the Bully-Banks campaign group, representing more than 2000 small firms across the UK.

The group says its typical SME member has laid off more than five employees as a result of an interest rate swap agreement (IRSA), and that seven out of 10 members would have created a further 12 jobs each had they not been burdened with the extra costs of their IRSA.

However, only a small proportion of the Clydesdale's TBLs are included in the mis-selling review of IRSAs being conducted by the banks and the Financial Conduct Authority.

The fixed rate version of the TBL, the most widely sold by the bank between 2000 and 2008, is unregulated by the FCA and the bank has resisted political pressure to include it in its review.

Crucially, the fixed rate TBLs carry built-in break fees, which experts say give them the same impact as IRSAs, adding liabilities that have prevented businesses from refinancing or expanding.

Clydesdale Bank said: "We have agreed with the FCA that we will conduct a review of the sale of our Interest Rate Hedging Products (IRHPs) and certain types of TBLs.

"However, to suggest that this is having a significant impact on the economy misunderstands the size and composition of the commercial real estate book and the nature of the economy. Not all CRE customers had IRHPs or TBLs or indeed experienced difficulties in their businesses."