The Islamic militant group Hamas claimed responsibility for a suicide bombing on Wednesday that killed eight Israelis on a bus near the northern Israeli city of Haifa. A statement issued by the group's armed wing Izz el-deen al-qassam and obtained by Reuters said, ''The operation, launched from the heart of our besieged cities, is a slap in the faces of the criminals of the Zionist war.'' The attack took place in the midst of a fierce, 12-day-old offensive by Israel in Palestinian-ruled areas of the West Bank which has continued in defiance of US and international demands to withdraw. Hamas said that one of its members ''penetrated all Zionist military barriers and reached Haifa,'' proving that the Israeli military campaign to prevent such attacks was not working. ''Jenin, Nablus, Tulkarm, Ramallah and Gaza will remain a nightmare for their defeated army,'' it added. Hamas, the main Palestinian group behind a wave of suicide attacks on Israelis during the 18-month-old uprising against Israeli occupation, vowed to mount further assaults. Bureau Report