"Economic concerns again become a bearish factor of the crude market," with prices "under pressure due to a large build in the U.S. stockpile and a hawkish Fed that led to a strong dollar," said independent market analyst Tina Teng.
fell at Asia's open on Monday, dragged down by a renewed focus on market fundamentals, as Israel and Iran played down the risks of an escalation of hostilities in the Middle East after Israel's apparently small strike on Iran.Brent futures fell 54 cents, or 0.6%, to $86.75 a barrel by 1218 GMT.
The front month U.S. West Texas Intermediate (WTI) crude contract for May, which expires on Monday, fell 12 cents to $83.02 a barrel. The more active June contract dropped 47 cents, or 0.6%, to $81.75 a barrel.
"Economic concerns again become a bearish factor of the crude market," with prices "under pressure due to a large build in the U.S. stockpile and a hawkish Fed that led to a strong dollar," said independent market analyst Tina Teng.
On Friday, Chicago Federal Reserve President Austan Goolsbee became the latest central banker to signal a longer timeline for interest rate cuts because progress on inflation had "stalled".
U.S. crude inventories rose by 2.7 million barrels, Energy Information Administration data showed last week. The increase was nearly double analysts' expectations of a 1.4 million barrel rise.
Last week, both oil benchmarks posted their biggest weekly loss since February after Iran downplayed reports of a presumed retaliatory Israeli air strike on its territory and said it did not plan to respond. Prices retreated on the news after initially spiking more than $3 a barrel.
On Saturday, the U.S. House of Representatives passed an aid package for Ukraine and Israel containing measures that would let the federal government expand sanctions against Iran and its oil production. But shrugged off the news as the impact of the measures, if passed, would depend on how they are interpreted and implemented.
Senate consideration of the bill is set to begin on Tuesday.
Iran is the third largest producer in the Organization of the Petroleum Exporting Countries (OPEC), according to Reuters data. Despite a wide range of existing U.S. sanctions, its oil shipments have increased due to from China and networks outside the U.S. financial system.
ANZ analysts said in a note that volatility in the Middle East will keep oil markets "jittery".
On Saturday, a blast at an Iraqi military base killed a member of a security force that includes Iran-backed groups. The force commander said it was an attack while the army said it was investigating.
Separately, on Sunday, Iran-backed Lebanese group Hezbollah said it downed an Israeli drone that was on a combat mission in southern Lebanon.
Israeli forces and Lebanon's armed group Hezbollah have been exchanging fire for over six months in parallel to the Gaza war, fuelling concerns about further escalation.