Oil prices gained further ground on Wednesday as supply concerns lingered after a winter storm disrupted US crude output and exports, while Middle East tensions lent additional support. Brent crude futures rose 28 cents, or 0.4%, to $67.85 a barrel by 0410 GMT, while US West Texas Intermediate crude climbed 35 cents, or 0.6%, to $62.74 a barrel. Both benchmarks surged about 3% on Tuesday. US