Brent hit its lowest since April in the previous session, at $42.56, while WTI hit a fresh low of $40.95 per barrel early on Friday, and both crude benchmarks are now down around 20% since their last peak in June.

Because of ongoing oversupply, US bank Goldman Sachs said this week that it did not expect a big recovery in prices any time soon.

"We continue to expect that oil prices will remain in a $45 per barrel to $50 per barrel trading range through mid-2017 with near-term risks skewed to the downside," the bank said.

Despite this, some analysts said recent price falls in oil had been overdone, especially as demand remains strong despite concerns over future economic growth.

"Investors have become overly bearish on oil as US production and gasoline inventories continue to rise. We think those concerns are unwarranted. Underlying demand in the US remains robust," ANZ bank said.