* U.S. crude stocks rose 6.8 mln bbls, surprising market
* Inventory build came despite record refinery runs
* World trade growth peaked in January -analysts
* U.S. sanctions against Iran to cut supply (New throughout, updates prices, market activity and comments to settlement)
By Jessica Resnick-Ault
NEW YORK, Aug 15 (Reuters) - Oil futures slid on Wednesday, with U.S. crude settling 3 percent lower after government data showed a surprise weekly increase in domestic crude stockpiles, compounding worries about the global economic growth outlook.
U.S. crude futures CLc1 settled at $65.01 a barrel, down $2.03, or 3 percent. Brent crude futures LCOc1 were down $1.70, or 2.35 percent, at $70.76 a barrel.
U.S. crude inventories last week USOILC=ECI rose 6.8 million barrels even though refinery crude runs hit a record high, Energy Information Administration data showed. Crude stocks at the Cushing, Oklahoma USOICC=ECI , delivery hub for U.S. crude futures rose 1.6 million barrels. EIA/S
Analysts polled by Reuters had expected a weekly decline. oil processing increased sharply and reached a record level of almost 18 million barrels per day last week," said Carsten Fritsch, senior commodities analyst at Commerzbank (DE:CBKG). "But this was not enough to prevent the inventory build. Or take it this way; it prevented an even larger build."
"Adding to the weakening price backdrop are signs that a deepening trade spat between the United States and China is undermining oil demand."
Investors are concerned about the world economy as trade disputes escalate between the United States and its major trading partners.
The OECD's composite leading indicator, which covers the western advanced economies plus China, India, Russia, Brazil, Indonesia and South Africa, slipped below trend in May and June.
World trade volume growth peaked in January, and since then has nearly halved to less than 3 percent by May, according to the Netherlands Bureau for Economic Policy Analysis. United States and China have been locked in a trade battle for months, pressuring economic activity in both countries.
Chinese importers appear to be shying away from buying U.S. crude oil as they fear Beijing may decide to add the commodity to its tariff list. a single tanker has loaded crude oil from the United States bound for China since the start of August, Thomson Reuters Eikon ship tracking data showed, compared with about 300,000 barrels per day (bpd) in June and July.
Investors were also watching the impact of U.S. sanctions on Tehran, which analysts say could remove as much as 1 million bpd of Iranian crude from the market by next year.
BMI Research said oil markets would "struggle for direction, as uncertainty around both the impact on supply from the Iranian sanctions and escalating trade tensions between the U.S. and China persists".
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