By Shariq Khan and Stephanie Kelly BENGALURU (Reuters) -Oil prices jumped on Monday to their highest levels since 2008 as the United States and European allies considered banning Russian oil imports while it looked less likely that Iranian crude would return switftly to global markets. By 12:45 p.m. EST (1745 GMT), Brent had gained $4.86, or 4.1%, to $122.97 a barrel, and U.S. West Texas Intermediate (WTI) rose $2.85, or 2.5%, to $118.53 a barrel. During the session, both benchmarks hit the highest since July 2008 with Brent hitting $139.13 a barrel and WTI $130.50. “The original spikes were o…