Weighing on financial markets were concerns that a trade dispute between the United States and China would remain unresolved, denting global economic prospects.
International Brent crude futures were down 14 cents at $61.49 per barrel at 0855 GMT. On the week, they are set for a loss of around 2 percent, the steepest weekly fall this year.
US West Texas Intermediate crude futures stood at $52.46 per barrel, down 18 cents, and looking at a 5 percent weekly slump.
US President Donald Trump said on Thursday that he did not plan to meet Chinese President Xi Jinping before a March 1 deadline set by the two countries to strike a trade deal.
If there is no agreement between the world's two biggest economies, Trump has threatened to increase US tariffs on Chinese imports.
On Thursday, the European Commission sharply cut its forecasts for euro zone economic growth due to global trade tensions and an array of domestic challenges.
Another factor weighing on oil prices this week was a strong dollar.
Despite this, traders said crude was prevented from falling much further by supply cuts led by the Organization of the Petroleum Exporting Countries, adopted late last year with the aim of tightening the market and propping up prices.
As part of the cuts, OPEC kingpin Saudi Arabia reduced its output in January by about 400,000 barrels per day (bpd) to 10.24 million bpd, OPEC sources said.
That puts Saudi crude oil production almost 1.7 million bpd below that of the United States, which has churned out around 11.9 million bpd in late 2018 and early 2019 - up more than 2 million bpd from a year earlier.
Another risk to supply comes from Venezuela after the implementation of US sanctions against the OPEC member's petroleum industry in late January. Analysts expect this move to knock out 300,000-500,000 bpd of exports.
For the time being, though, the sanctions impact on international oil markets has been limited.
"The (Venezuela) disruption overall seems manageable both for the US and the global market," said Norbert Ruecker, head of commodity research at Swiss bank Julius Baer.