Oil prices fell on Monday, with U.S. crude slipping to a 3-month low on rising concerns that a global glut of crude and refined products would pressure markets.
Data from market intelligence firm Genscape pointed to an inventory rise of 1.1 million barrels at the Cushing, Oklahoma delivery base for U.S. crude futures in the week to July 22, said traders who saw the numbers.
Investors have become less optimistic that markets will balance quickly amid a massive overhang in refined products, particularly gasoline, despite forecasts for record U.S. summer driving.
"We've got gasoline stocks that are through the roof ... And you have the specter of turnaround season not too far in the horizon," Robert Yawger, senior vice president of energy futures at Mizuho Securities USA said.
Yawger cut his price target on U.S. crude to $40 from $45 a barrel.
The threat of resurgent U.S. oil production with the rise of drilling rigs and a strong dollar added to the gloomy sentiment in the market, traders and brokers said.
Brent crude futures were trading at $44.65 a barrel by 4;25 p.m ET, down $1.04 cents or 2.28 percent from their previous close. The contract fell to an intraday low of $44.55, a low going back to May 10.
U.S. crude settled down $1.06, or 2.4 percent, at $43.13 a barrel and was last down $1.14, or 2.58 percent, at $43.05 a barrel, having earlier touch $42.97, their lowest level since April 26.
The settle marked the lowest since April 25, when oil settled at $42.64 per barrel.
"Supply continues to return from disruptions, refined products are severely oversupplied, crude demand is falling well short of product demand, and key product demand is decelerating," Morgan Stanley said in a note.
The decline in U.S. output has been key to balancing a market that has been grappling with excess crude for nearly two years, but with prices recovering from 12-year lows, signs of drilling activity have re-emerged.
U.S. drillers added oil rigs for a fourth consecutive week, according to last week's data from a closely followed report by energy services firm Baker Hughes.
But it could be premature to assume it could lead to a rise in production, some analysts said.
"Although drilling activity is now at its highest level since the end of March, it is still 30 percent below the level at which it found itself at the beginning of the year." Commerzbank analysts said in a note.
Barclays bank said global oil demand in the third quarter of 2016 was expanding at less than a third of the year-earlier rate, weighed down by anemic economic growth.
Globally, demand support from developed economies had faded, while growth from China and India had slowed, Barclays said.
New tensions in Libya highlight that the OPEC member is unlikely to see a significant boost to its oil exports any time soon, after the national oil corporation said it objected to a deal to reopen key ports.