Investing.com - Oil prices edged lower during European morning hours on Monday, starting the week off in negative territory as rising U.S. shale production continued to feed concerns about a global supply glut.
The U.S. West Texas Intermediate crude June contract shed 15 cents, or around 0.3%, to $49.18 a barrel by 3:40AM ET (07:40GMT).
Elsewhere, Brent oil for July delivery on the ICE Futures Exchange in London dipped 20 cents to $51.85 a barrel.
Trading activity was expected to remain light on Monday, with most markets in Europe, the U.K. and Asia closed for the May Day holiday.
Crude has been under pressure in recent weeks amid fears that an ongoing rebound in U.S. shale production is derailing efforts by other major producers to rebalance global oil supply and demand.
U.S. drillers last week added rigs for the 15th week in a row, data from energy services company Baker Hughes showed on Friday, implying that further gains in domestic production are ahead.
The U.S. rig count rose by 9 to 697, extending an 11-month drilling recovery to the highest level since August 2015.
The relentless increase in U.S. output has overshadowed pledged output cuts by major producers.
In November last year, OPEC and other producers, including Russia agreed to cut output by about 1.8 million barrels per day between January and June, but so far the move has had little impact on inventory levels.
A final decision on whether or not to extend the deal beyond June will be taken by the oil cartel on May 25.
Iran's oil minister said on Saturday that OPEC and non-OPEC countries had given positive signals for an extension of output cuts, which Tehran would also back.
Elsewhere on Nymex, gasoline futures for June held steady at $1.541 a gallon, while June heating oil slipped 0.3 cents to $1.503 a gallon.
Natural gas futures for June delivery inched up 0.4 cents to $3.280 per million British thermal units.