Oil prices climbed nearly 6 per cent on Friday, with benchmark Brent posting its highest weekly gain since February, as investors priced in the possibility that the conflict in the Middle East could widen as Israel began ground raids inside the Gaza Strip. Israel's announcement marked a shift from an air war to ground operations to root out Hamas fighters a week after the militant Palestinian group's deadly rampage in southern Israel. Chaos broke out after some residents in Gaza were abandoning their homes on Friday to escape from the path of an Israeli onslaught, after Israel ordered more than…