The price of oil fell to a more-than 12-year low on Monday, adding to concerns that the lifting of sanctions against Iran will boost the global oversupply of the commodity.
Brent crude dropped to 27.67 dollars a barrel - its lowest price since 2003. US crude also slumped to a more-than 12-year low of 28.36 dollars a barrel.
The world's two benchmark oil prices have dropped by about 25 per cent since the start of the year amid worries about the world economic outlook and a surplus of US shale oil surging onto the market.
Global shares also came under renewed pressure on Monday following worries about the prospects for global growth, in particular as a result of a slowdown in China.
The eurozone's blue-chip Euro Stoxx 50 slipped 0.5 per cent in early morning trading on Monday after stocks in parts of Asia also closed down.
The fresh drop in the oil price on Monday came in the wake of the weekend announcement that US and European economic sanctions imposed on Tehran had been lifted.
The International Atomic Energy Agency confirmed Saturday that oil-rich Iran had scaled down its nuclear programme and fulfilled its obligations under a July nuclear deal with six world powers.
Tehran has already announced plans to ramp up crude oil exports to about 500,000 barrels a day, which is likely to further increase the global oversupply.