Oil rose for a third straight session on Tuesday to more than $138 a barrel, following rumors of an attack on Iran's nuclear facilities, which was later denied, Reuters reported. "This is just a rumor. No attack against Iran's nuclear facilities has taken place," a senior Iranian nuclear official said. Israeli and American military spokesmen also denied the rumors, according to Bloomberg. US crude for August delivery was up a $1.33 at $138.07 a barrel, after settling up $1.38 on Monday. It hit a record high of $139.89 on June 16. London Brent crude was up $1.31 at $137.22 a barrel. Tension over Iran's nuclear program has played a big part in oil's rise to record levels near $140 a barrel. The European Union this week imposed new sanctions on Iran, including as asset freeze on Bank Melli, Iran state-controlled and biggest bank. On Friday, The New York Times quoted unnamed US officials as saying Israel had carried out a wide scale military exercise, apparently as a rehearsal for a potential bombing of Iran's nuclear facilities. Analysts are worried heightened tensions between Iran and the West could threaten the Straits of Hormuz, a narrow waterway separating Iran from the Arabian Peninsula through which roughly 40 percent of the world's traded oil flows.