World oil futures fell below 70 dollars Tuesday on hearing that Tropical Storm Ernesto would avoid Gulf of Mexico oil installations.
New York's main contract, light sweet crude for delivery in October, closed down 90 cents at 69.71 dollars per barrel.
In London, Brent North Sea crude for October delivery settled 75 cents lower at 69.86 dollars per barrel.
Hurricane Ernesto,the first hurricane of the Atlantic season this Year, was downgraded to a tropical storm late Sunday. It swept Haiti and the Dominican Republic Sunday with heavy rains, and was expected to move over Cuba and could hit southern Florida by Tuesday, according to the Miami, Florida-based National Hurricane Center.
Hurricanes Rita and Katrina in 2005 have destroyed the oil and gas production platforms and rigs in Gulf of Mexico and led to record highs in crude futures market.
Meanwhile, traders are worried that Iran's oil exports would stop if the United Nations imposes sanctions against Teheran for its nuclear activities.
Iran is OPEC's No. 2 producer following Saudi Arabia, pumping 4 million barrels of crude oil and exporting 2.4 million barrels per day.