Hong Kong/New York CNN  —  Global oil prices have had their largest single-day percentage increases in years, reflecting fears that a wider conflict in the Middle East could lead to serious energy supply disruptions. Brent crude, the global benchmark, was last up 4.3% at $72.4 a barrel on Friday. West Texas Intermediate, the US benchmark, jumped 5% to $71.4 a barrel, after gaining as much as 13% earlier in the day. According to Reuters, they are the biggest intraday gains for each benchmark