Central Bank Governor Professor Patrick Honohan has said higher bank capital ratios and more disclosure about residential mortgage loans are key steps to rebuilding confidence in the Irish banking sector. He said concern about risk in the banks' portfolios, together with heightened market uncertainty, argues for higher percentage capital targets. This refers to the level of funds the banks must hold in reserve to act as a cushion against possible losses. Bank shares were sharply lower in Dublin this lunchtime, amid uncertainty about what measures are being planned to restructure the banking system. Bank of Ireland shares had fallen by 20% this afternoon, while AIB shares were down 15%.