Israeli aircraft attacked the office of Palestinian Prime Minister Ismail Haniyeh of Hamas in Gaza City early Sunday, witnesses said, setting the building on fire. There were no immediate reports of casualties. The Israeli army had no comment. Witnesses said two missiles hit the south side of the building, setting it ablaze. Because of the late hour - 1:45 a.m., the building was empty, they said. On Thursday, Israeli planes attacked the Interior Ministry, part of Israel's campaign to force release of a soldier abducted by Palestinian militants last Sunday.