Oil fell below $115 a barrel on Friday as signs of weakness in the global economy weighed on the demand outlook, although a host of supply-side concerns kept losses in check.
Crude was still heading for a fourth weekly gain because of lower exports from Iran, a drop in North Sea supply due to oilfield maintenance and the risk of weather-related disruption to Gulf of Mexico output.
Brent crude was down 45 cents at $114.56 a barrel by 1103 GMT, up about 0.8 percent on the week. U.S. crude eased 42 cents to $95.85.
"Falling equity markets and poorer economic data from the three major oil consumer regions - the United States, China and Europe - have put paid to the surge in oil prices for the time being," said Carsten Fritsch, analyst at Commerzbank.
European equities were lower on Friday, weighed by concern about the euro zone debt crisis. Reports on Thursday showed China's factory sector contracted in August and a rise in new U.S. jobless claims.
Brent's settlement on Tursday at $115.01 was just barely above $115, a technical level that has stood in the way of a further rally this week. Thursday's close was not strong enough to overcome the resistance, one chart-watcher said.
"We do not consider it enough. If the level fails again tonight then the weekly charts will reinforce the resistance status of $115.00," said Olivier Jakob, analyst at Petromatrix.
Investors are speculating about the prospect of strong monetary stimulus from the U.S. Federal Reserve. Fed Chairman Ben Bernanke and other central bank leaders meet in Jackson Hole, Wyoming, next week.
Iran and the fighting in Syria remain a focus for the market. Iran is holding talks on Friday with the U.N. nuclear watchdog about the Islamic state's atomic activities.
Iranian oil exports have plunged due to Western sanctions over the country's nuclear programme, and diplomatic sources said on Thursday Iran had installed many more uranium enrichment machines in an underground bunker.
Oil traders are also keeping an eye on Tropical Storm Isaac in the Atlantic for any risk it may threaten U.S. energy supplies in the Gulf of Mexico.
Analysts at Weather Insight, a Thomson Reuters company, gave Isaac a 50 percent chance of moving into the heart of the oil and gas producing region. Another storm, Joyce, has weakened to a depression. (Reporting by Alex Lawler, and Ramya Venugopal and Wang Tao in Singapore; Editing by Anthony Barker)