Oil prices edged up on Tuesday after a volatile session the previous day, with the impact of tension in the Middle East offset by worries over global economic growth. Global oil benchmark Brent (LCOc1) was up 22 cents at $37.44 a barrel by 0142 GMT, after hitting a three-week high of $38.99 on Monday as relations between Middle Eastern rivals Saudi Arabia and Iran deteriorated following Riyadh’s execution of a prominent Shi’ite Muslim cleric. U.S. crude’s West Texas Intermediate (WTI) futures were up 28 cents at $37.04 (CLc1).