Feb 20 - Oil prices were higher on Friday as concern of conflict between the U.S. and Iran ratcheted up, with Washington saying Tehran will suffer if it does not agree a deal about its nuclear activity within a matter of days. Brent crude futures rose 21 cents, or 0.3 per cent, to $71.87, while U.S. West Texas Intermediate crude gained 23 cents, or 0.4 per cent to $66.66. Prices settled at their highest in six months on Thursday after U.S. President Trump said "really bad things" would happen