The price of Brent crude declined below $97 a barrel and is set for its worst month since April 2013 due to excess supply.
Reuters reported that Brent declined 37 cents at $96.63 a barrel in November and US crude slipped 20 cents to settle at $92.33 a barrel.
US-led strikes against IS militants in Syria and the disruption of oil production in Iraq have had no major impact on the prices of Brent.
Although oil supply is on the rise, Europe and Asia’s slowing economic activity has dampened oil demand.
Oil production touched 925,000 barrels per day (bpd) in Libya, marking the highest level since the clash of militias following the death of Muammar Gaddafi.
Additionally, refinery outages and higher US gasoline futures could not boost the price of crude in the US.
VTB Capital analyst Andrey Kryuchenkov was quoted by Reuters as saying: "At the moment, supplies are abundant and demand is weaker."
Oil prices are expected to be under pressure until European refineries resume operations in November following the completion of the maintenance period and the Organization of the Petroleum Exporting Countries (OPEC) meeting, which is scheduled for November.
The meeting will focus on whether to adjust the output target of 30 million bpd for early 2015.
Iranian Oil Minister Bijan Zanganeh has urged OPEC members to "make joint efforts" in order to stop the further decline of oil prices.