Oil rose to its highest in a week on Tuesday, buoyed by the prospect of price support from U.S. sanctions on Iran, although the trade dispute between Washington and Beijing kept traders and analysts cautious.
Brent has rallied more than 3 percent after touching a four-month low last week, while U.S. crude is up nearly 5 percent from last Thursday's eight-week low.
U.S. West Texas Intermediate crude for delivery in September jumped 92 cents, or 1.4 percent, to end the session at $67.35. The contract expires on Tuesday.
September WTI's premium to the October contract widened to as much as $1.69 a barrel on Tuesday, after narrowing since the beginning of August. The front-month spread widened significantly in July after an unexpected outage at Canada's oil sands facility dented flows of crude into Cushing, Oklahoma, the delivery point for U.S. futures.