The Swiss franc firmed in early trade on Tuesday as security concerns sparked fresh safe-haven buying of the franc after Israel killed the spiritual leader of the militant Hamas group. Fears of renewed violence in the Middle East weighed on the dollar , which eased to 1.2559/64 francs from 1.2576/81 late on Monday. The euro changed hands at 1.5514/18 after 1.5545/50. With the assassination, Israel dealt its heaviest blow against Hamas which has been behind dozens of suicide bombings. The killing drew vows of revenge from Hamas. The Swiss currency tends to firm in times of geopolitical unrest as investors switch dollars assets into "safe-haven" francs.//