Oil prices slid on Monday in volatile trade that saw an early rally of more than 4 percent on tensions in the Middle East until those gains were erased on worries about a slowing global economic growth and sliding stock markets.
Data showing an inventory build at the Cushing, Okla. delivery hub for U.S. crude futures also weighed on sentiment, traders said.
Brent, the global oil benchmark, fell 5 cents, or 0.13 percent, at $37.24 a barrel, having hit an intraday high of $38.99.
U.S. crude's West Texas Intermediate (WTI) futures settled 28 cents lower, or 0.76 percent at $36.76 a barrel.
WTI was also weakened by data from market intelligence firm Genscape that showed a build in Cushing supply, traders who saw the data said.