Brent North Sea for delivery in August slid 55 cents to stand at USD 108.12 a barrel in London early afternoon deals.
US benchmark West Texas Intermediate for August reversed 45 cents to USD 102.48 per barrel compared with yesterday's close.
Sanjeev Gupta, head of the Asia-Pacific oil and gas practice at consultancy firm EY, said oil prices were weighed down by the imminent return of disrupted Libyan exports into a global market already flush with supply.
Brent crude has fallen more than USD 3.0 since July 3 after Libya's interim Prime Minister Abdullah Al-Thani declared that authorities had regained control of two export terminals blockaded by rebels.
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Output in Sharara, the site of Libya's largest oil field, is reaching its maximum production capacity of 340,000 barrels just days after it was reopened following a deal between rebels and the government, the Wall Street Journal reported.
Unaffected production in violence-hit Iraq has also had a bearish impact on oil prices, Gupta said.
"Indications that Iraqi oil exports from the southern part of the country remained insulated from the sectarian violence that has swept the north in recent weeks also weighed down prices," he said.