WTI crude for October delivery finished at $104.67 a barrel in New York, down USD 1.72 from yesterday. Brent North Sea crude for November meanwhile gained 46 cents to stand at USD 109.22 a barrel in London deals.
"The main focus has returned to the oil (supply and demand) fundamentals, especially due to the increasing oil production in Libya," said Myrto Sokou, senior research analyst at Sucden brokerage.
Analysts said the return of some production of Libyan oil fields and the easing of tensions in the Middle East after Syria agreed to a plan to put its chemical weapons arsenal under international control helped ease prices.
Protests by oil field and export terminal workers since July had crippled Libyan production. Crude prices were also tempered by fresh comments from Iran's new President Hassan Rowhani seen as constructive toward restoring relations with the West.
Speculation is rising that Tehran's new tone could lead to a rapprochement with the United States.