Crude oil prices were heading for a weekly loss on Friday due to concerns over the glut of oil supply in the global market and the possibility of oil demand worldwide remaining low this year.
The price of Brent crude traded at $63.49 per barrel at 1120 GMT Friday for a 0.3% daily gain, but the international benchmark was heading for a 2.4% loss after it opened Monday at $65.05 a barrel.
American benchmark West Texas Intermediate was $56.89 a barrel at the same time for a 0.16% daily increase, however it declined to almost 4% after it started the week at $59.27 per barrel.
Both benchmarks decreased by more than 4% on Tuesday despite the announcement of OPEC+ oil producing countries on their agreement to extend their production cut deal for nine months until March 31, 2020.
The extension will see OPEC and Russia continue curbing their total oil production level by 1.2 million barrels per day, although the market expected an increase to this level in order to rid market oversupply.
On the demand side, the trade conflict between the U.S. and China, the world's two largest oil consumers, continues to put pressure on the global economy and overall oil demand around the world.
U.S. President Donald Trump and his Chinese counterpart Xi Jinping met Saturday at the G20 leaders' summit but the dispute between the world's two biggest economies continues without any resolution in sight.
"Cooperation and dialogue are better than friction and confrontation," Xi said before he and Trump went behind closed doors for discussions in Osaka, Japan.
Trump on his Twitter account said the two leaders have opened up trade negotiations between their countries, and added, "Our relationship with them continues to be a very good one."
By Ovunc Kutlu