NEW YORK, May 18 (Reuters) - Oil prices slipped in choppy trade on Friday, heading for a third straight weekly loss as Greece's political uncertainty kept concerns about the euro zone in focus, while short-covering after recent losses helped limit oil's slide.
European officials are working on contingency plans in case Greece exits the euro zone, the EU's trade commissioner said on Friday, while Berlin said it was prepared for all eventualities.
Oil felt pressure early from data showing Chinese home prices in April fell for a second month in a row from year ago levels.
Position squaring after this week's expiration of Brent's June contract and U.S. June crude options and caution ahead of the weekend's Group of Eight meeting, traders and analysts said.
Also in focus is this weekend's planned start of crude oil flows on the reversed Seaway pipeline.
The reversal is intended to ease a glut of crude in the U.S. Midwest by bringing it via Seaway to the refinery-rich Gulf Coast and reducing Brent's premium to its U.S. counterpart.
Brent July crude fell 51 cents to $106.98 a barrel by 11:35 a.m. EDT (1535 GMT), having fallen to a 2102 low of $106.40, lowest intraday price since Dec. 21, and on pace to post a 4-percent weekly loss.
U.S. June crude was down 50 cents at $92.06, after dropping to a 2012 low of $91.60, the lowest intraday price since Nov. 3. U.S. crude also faced a 4 percent weekly drop.
The U.S. June contract expires on Tuesday.
The choppy trading trajectory left the Brent/U.S. crude spread little changed near $14.65 a barrel CL-LCO1=R based on July crude contracts.
"It's the fear factor that's driving Brent," agreed Guy Wolf, macro strategist at Marex Spectron in London. "Finally Europe has reached the key Greece in/Greece out moment."
If Greece leaves, this could trigger bank runs in Italy and Spain, he added, seeing the possibility of a major impact on growth.
