Oil prices fell on Monday as the latest increase in the number of drilling platforms in the United States indicated another increase in US production, threatening to undermine efforts led by the Organization of Petroleum Exporting Countries (OPEC) to curb the supply of oil in the markets.
US West Texas Intermediate crude futures traded at $ 57.05 a barrel at 0219 GMT, down 31 cents, or 0.5 percent, from the last close.
Brent crude futures fell 34 cents, or 0.5 percent, to $ 63.06 a barrel.
Drilling companies added two oil diggers in the week ending Dec. 8, bringing the total to 751, the highest since September, Baker Hughes Energy Services said on Friday.
The increase in the number of drilling rigs suggests another increase in US crude oil production, which has already increased more than 15 percent since mid-2016 to 9.71 million bpd.
It is the highest level of production in the United States since the early 1970s and is close to the production level of Russia and Saudi Arabia, the two largest producers of crude oil.
High US output threatens to undermine efforts by the Organization of Petroleum Exporting Countries (OPEC) and a group of non-OPEC oil producers, particularly Russia, to boost prices by cutting oil supplies.