Crude plunged by more than $2 per barrel on Friday, heading for a third straight weekly loss as worries about supply disruptions in the Middle East and North Africa eased.
Brent and U.S. crude prices had recovered in the previous session, ending their longest streak of daily losses in years. But in intraday trading the selling picked up again, sending the international contract down by more than $2 to under $107 a barrel, while U.S. crude fell by $2.12 to settle at $100.83
Supply concerns eased in the Middle East and Africa despite geopolitical tensions in Iraq, Libya and Gaza. Libya's southern El Sharara field is boosting production and has pushed the country's oil output to 350,000 barrels per day, a spokesman for National Oil Corp said on Thursday.
Analysts warned, however, that it would take months to ramp up production and more unrest is possible.
In Iraq, exports from southern Basra ports continued despite an ongoing Islamic insurgency. Sunni militants battling forces loyal to Iraqi Prime Minister Nuri al-Maliki broke into a military base in Diyala province northeast of Baghdad on Thursday, a security source and a local official said.
Meanwhile, investors are looking ahead to second quarter GDP data from China next week to assess fuel demand outlook at the world's second largest consumer.