Worries that the European debt crisis could spread to other countries following Ireland's acceptance of a bail-out sent shares in banks lower Monday.While markets initially moved higher as investors breathed a sigh of relief when the Irish government put an end to lingering uncertainty about accepting a bail-out, shares soon fell back amid worries over whether the bail-out will really solve underlying problems.Bank of Ireland, which is listed in Dublin and London, was sharply lower, amid worries that the bail-out, which Ireland's government intends to use to stabilise its banking sector, would dilute existing shareholders' stakes. Fellow bank Allied Irish and bancassurer Irish Life & Permanent were also sharply lower.Royal Bank of Scotland, which has strong exposure to Ireland on both sides of the border through its subsidiary Ulster Bank, was also nursing significant losses. Ireland's finance minister Brian Lenihan says the government will scale back the size of its banks by offloading overseas and non-essential assets.