Oil prices have continued to fall on Monday, despite last week's 1.5 million-barrel-a-day cut in production from oil producers' cartel Opec.
US light sweet crude for delivery in December dropped to a 17-month low of $61.30 a barrel before recovering somewhat to trade at $62.42.
London Brent crude fell below $60 a barrel before recovering to $61.32.
The falls have been blamed on worries about how much a global economic slowdown will hit demand for oil.
"The mood is fairly negative reflecting worry about the international economic outlook," said David Moore at Commonwealth Bank of Australia.
"If there is further weak economic data in the US or Europe, prices could come under more downward pressure."