Brent crude oil slid below $103 a barrel on Friday after rising $3 in the past two sessions as investors were cautious over the tepid outlook for growth in the world's two largest oil consumers, the United States and China.
The oil price is set for its biggest weekly gain since November but is still 7 percent off levels at the start of April after a string of disappointing data stoked fears of global economic slowdown.
Brent slipped 66 cents to $102.75 a barrel by 1030 GMT, after touching a low of $102.56, while U.S. crude was down 63 cents at $93.01.
"Crude is being driven by strong momentum from the U.S., so we're seeing a bit of profit-taking now," said Olivier Jakob, oil analyst at Petromatrix in Zug, Switzerland.
"The U.S. GDP numbers are out later, and that's something we need to watch.
Brent's premium to U.S. crude futures edged lower after settling at below $10 on Thursday for the first time since January 2012.
"The market has gone through a period of relatively robust North Sea production, thus weakening the Brent side of the spread, while market participants are less concerned with the overhang of crude oil in the U.S. Midwest as the ability to move oil out of the region continues to increase," Dominick Chirichella of Energy Management Institute said.
Weak economic numbers from China and the euro zone have weighed on Brent, while better-than-expected U.S. data and the easing of a supply glut at Cushing, Oklahoma, the delivery point for U.S. crude futures, have buoyed the U.S. marker.
U.S. crude is on track for its largest weekly rise since July 2012, and prices could climb further if first-quarter GDP growth, due for release later on Friday, meets expectations.
Economists expect a 3.0 percent annualised pace of growth compared with 0.4 percent the quarter before, a Reuters survey showed.
"It's quite a big jump, and if it comes in line with expectations, that will be supportive for markets," ANZ's Rampono said.
Oil was also supported by a tightening of global spare inventories over the past two months, according to a report from the U.S. Energy Information Administration, as well as by ongoing tensions in the Middle East.
Members of the U.S. Congress are calling for action on Syria after a report showed the likely use of chemical weapons by the Syrian government. (Additional reporting by Florence Tan; in Singapore; Editing by William Hardy and Jane Baird)