By Bassam Masoud, Nidal al-Mughrabi, Emily Rose GAZA/JERUSALEM (Reuters) -Twenty-four Israeli soldiers were killed in Israel’s worst day of losses in Gaza, the military said on Tuesday while also claiming to have encircled southern Gaza’s main city and killed dozens of Palestinian fighters in a major ground assault of the new year. Spokesman Rear Admiral Daniel Hagari said 21 soldiers were killed when two buildings they had mined for demolition exploded after militants fired at a nearby tank. Earlier, three soldiers were reported killed in a separate attack in southern Gaza. “Yesterday we expe…