Crude oil surged to a record close of $138.54 in New York trade, gaining more than $10 in its biggest one-day jump ever after smashing a series of price hurdles.
New York's main oil futures contract, light sweet crude for July delivery, leapt $10.75 from Thursday's close.
In London, Brent North Sea crude for July crossed $138 for the first time and hit $138.12 a barrel. It eased back to $137.93 , up $10.39, shortly before the market closed.
Analysts said the sharp price spike was a reaction to remarks by an Israeli deputy prime minister warning that Iran would face attack if it pursues what he said was its nuclear weapons programme.
"If Iran continues its nuclear weapons program, we will attack it," said Shaul Mofaz, who is also transportation minister.