JERUSALEM, April 1 - Israel's defense minister Avigdor Liberman rejected on Sunday calls for an inquiry into the killing of 15 Palestinians by the military during a Palestinian demonstration that turned violent on Friday at the Israel-Gaza border.Hamas, the dominant Palestinian group in Gaza, said five of the dead were members of its armed wing. Israel said eight of the 15 belonged to Hamas, designated a terrorist group by Israel and the West, and two others came from other militant factions.U.N. Secretary-General Antonio Guterres has called for an independent investigation into Friday's bloodshed.His appeal was echoed by Federica Mogherini, the European Union's foreign policy chief, Amnesty International, and by Tamar Zandberg, leader of the Meretz party in Israel."Israeli soldiers did what was necessary. I think all our soldiers deserve a medal," the defense minister, Avigdor Liberman, told Army Radio. "As for a commission of inquiry - there won't be one."