* Greece concerns linger despite vote
* IEA signals leave market confused
* Brent shows biggest quarterly decline in a year
* US crude posts largest quarterly drop since end 2008 (Recasts; updates prices, market activity)
By Antonita Devotta
NEW YORK, June 30 (Reuters) - Brent crude futures finished slightly higher in seesaw trading on Thursday, with investors concerned about violence in Greece and uncertainty surrounding the IEA's emergency oil release plan.
Brent
U.S. crude
Volumes were thin, with U.S. crude trading 30 percent off and Brent crude dealings 9 percent off their 30-day averages.
"With U.S. trade winding down for the end of the quarter and the July 4th holiday coming up, we may be seeing some pause in frantic activity, with traders less willing to open new positions," analyst Tim Evans of Citi Futures Perspective said.
U.S. crude futures fell for the second straight month, ending June down 7.4 percent amid evidence of an economic slowdown in the Unites States, the world's largest oil consumer.
But for the year so far, crude prices remain up as the civil war in Libya has disrupted exports. Brent is up 18 percent so far in 2011, with U.S. crude up 4 percent.
On Thursday, oil drew some support from U.S. data showing factory activity in the Midwest picked up in June, fostering hopes for third-quarter economic growth. [ID:nN1E75T07N]
For the day, crude also drew support from higher product
prices. The front-month heating oil contract
"Products went off very strong, and lent support, and the dollar was weak all day. We settled just above the close on the day before the IEA action," said Stephen Schork, president at the Schork Group in Villanova, Pennsylvania
"The IEA challenged speculators to a game of chicken and they may make the U.S. administration pay."
The International Energy Agency (IEA) announced last week that it was releasing emergency stockpiles of oil last week to fill the gap left by the disruption to Libya's output.
WEIGHING OIL DOWN
Oil's gains during Thursday's session were capped by a steep decline in the broader commodities complex, which tumbled when a report from the U.S. Department of Agriculture put domestic corn supply way above estimates, adding that a bumper crop could be on the way. [ID:nN1E75T0AR]
The report shocked forecasters and shoved grain markets sharply lower, sending the Reuters-Jefferies CRB index <.CRB>, a commodities benchmark, down as much as 1 percent for the day. Oil represents about 25 percent of the index.
Violence worsened in Athens after the Greek Parliament approved an implementation bill for a 28-billion euro package of austerity measures required under a European Union/International Monetary Fund bailout. [ID:nL6E7HT0Z7]
Lawmakers voted by a clear margin for the five-year framework of spending cuts, tax rises and state asset sales, handing a 155-138 vote victory to Prime Minister George Papandreou.
Comments from European Central Bank chief Jean-Claude Trichet reinforced expectations of an interest rate hike next week. The euro hit a three-week high against the dollar, triggering oil's early jump.
"The eubilience from the resolution of the Greek debt crisis is yielding to the realities of a challenged demand landscape given the recent economic data," said John Kilduff, partner at Again Capital LLC.
"While there may be some signs that current economic soft patch has hit bottom, a real upswing is not near either."
IEA RELEASE PLANS CLOUDED BY UNCERTAINTY
Meanwhile, the International Energy Agency has sent conflicting signals to the market this week. Some traders and analysts said the agency's planned 60 million barrel crude and oil product release has been badly coordinated outside the United States. [ID:nL6E7HU13F]
The Netherlands will hold a tender for sale of up to 700,000 barrels of crude oil on Friday, as part of the IEA stock release programme, while Germany has said its 2.1 million barrels of crude sales offered will be mostly Iranian heavy crude. [ID:nnLDE75T0US]
JP Morgan analyst Lawrence Eagles said the varying auction methods in Europe and Asia may see less than a third of 30 million barrels earmarked for release in those countries taken up by traders, though he expected the vast majority of the 30 million barrels from the United States to be sold.
"The difference in the way oil is supplied to the market not only makes the release less effective, but also acts as a political barrier to a further emergency release by the IEA," Eagles said.
The U.S. Energy Department said it received more than 90 offers to purchase oil from the SPR, adding the offering of 30.2 million barrels of light, sweet crude oil was substantially oversubscribed. [ID:nWNA2640]
All contracts with the winning companies will be completed by July 11, at which time the department said it would provide details about the companies and the prices they paid for the oil. (Additional reporting by Gene Ramos, David Sheppard, Barani Krishnan and Robert Gibbons in New York, Jessica Donati in London and Florence Tan in Singapore; Editing by David Gregorio)