Investing.com - Oil futures pulled back on Monday, after U.S. President Donald Trump took to Twitter to slam OPEC about pushing prices higher.
"Oil prices getting too high. OPEC, please relax and take it easy. World cannot take a price hike - fragile!" Trump tweeted in his latest attack on the cartel.
U.S. West Texas Intermediate crude futures for March delivery on the New York Mercantile Exchange slumped 52 cents, or around 0.9%, to $56.78 a barrel by 7:15AM ET (12:15 GMT).
Elsewhere, Brent oil for April delivery on the ICE (NYSE:ICE) Futures Exchange in London shed 67 cents, or about 1%, to $66.58 a barrel.
Both benchmarks reached their highest levels of the year on Friday.
After ending 2018 in freefall, oil prices have rallied approximately 25% to start the year, boosted by efforts by global producers to cut supply.
In December, OPEC and a group of 10 producers outside the cartel, led by Russia, agreed to collectively cut production by a total of 1.2 million barrels per day (bpd) during the first six months of 2019.
Top exporter and OPEC's de facto leader Saudi Arabia recently pledged to cut even more production than the deal called for.
Trump's call comes after he announced U.S. sanctions against Iran and Venezuela that have caused output to fall in both countries. Output from Libya is also running below traditional levels because of the country's civil war.
Crude futures were also generally supported by hopes that the U.S. and China would soon resolve their trade disputes, which have dragged on global economic growth.
President Trump said on Sunday that he would delay an increase in tariffs on Chinese goods that had been scheduled for Friday, citing "substantial progress" in U.S.-China trade talks over the weekend. Crude prices had risen on the back of that news because of the reduced likelihood of a further economic slowdown in China, the world's biggest importer.