Converted banks are under fire from IFAs for protecting their profit margins and penalising borrowers.
IFAs argue banks are pandering to their shareholders by failing to pass on the full benefit of the Bank of England's Monetary Policy Committee 0.25 per cent April base rate cut.
Halifax and Abbey National only cut their rates by 0.1 per cent and other lenders including Alliance & Leicester have so far failed to react.
Despite banks arguing they have to protect savers Abbey National has cut rates on savings accounts by 0.2 per cent and IFAs believe that banks can afford to cut mortgage rates.
IFAs are supported by Building Society Association latest figures showing net interest margins for mortgage and savings business. Halifax has a 2.43 per cent margin, Abbey National 2.39 per cent compared to Bradford & Bingley 1.31 per cent and Coventry Building Society 1.24 per cent.
John Charcol technical manager Ray Bulger says: "I would like to ask the converted banks why they were able to pass on the last interest rate cut but not this one. They have access to wholesale moneymarkets and are much less reliant on retail savers than mutuals.