LONDON—Oil prices jumped on Monday as Western allies imposed more sanctions on Russia and blocked some Russian banks from a global payments system, which could cause severe disruption to its oil exports. Brent crude rose $2.65, or 2.7 percent, to $100.58 by 1255 GMT after touching a high of $105.07 a barrel in early trade. The Brent contract for April delivery expires on Monday. The most active contract, for May delivery, was up $3.68 at $97.80. U.S. West Texas Intermediate (WTI) crude was up $3.62, or 4 percent, at $95.21 after hitting $99.10 in early trade. “Growing concerns about disruptions to Russian energy supplies are pushing oil and gas prices up sharply,” said Commerzbank analyst Carsten Fritsch. Russia is facing severe disruption to its exports of all commodities from oil to grains after Western nations imposed stiff sanctions on Moscow and cut off some Russian banks from the SWIFT international …