Brent rebounded from its biggest loss in three weeks as the U.S. said it will toughen sanctions on Russia , the biggest energy exporter, over the Ukraine crisis. West Texas Intermediate rose after a weekly decline. Futures advanced as much as 0.6 percent in London . The U.S. and European Union will announce new sanctions as early as today on Russian companies and individuals close to President Vladimir Putin , officials said. Among those that may be targeted are Igor Sechin , chief executive officer of OAO Rosneft, the country’s biggest oil producer, people familiar with developments said. “The price is being supported by uncertainty as to the breadth and impact of sanctions taken against Russia,” Christopher Bellew , a senior broker at Jefferies Bache Ltd. in London, said by e-mail. “Another important consideration is how Russia might retaliate against sanctions.” Brent for June settlement climbed as much as […]