SINGAPORE, Sept 2 (Reuters) - Middle East crude rose on Friday sending Oman's premium to a three-month high as European buyers drained supplies, boosting arbitrage flows opened by a strong Urals market. Three to four Oman cargoes for loading in September and October were expected to head to the Mediterranean as refiners there stock up on crude supplies in the run-up to the heating season. Spot Oman cargoes for loading in November were notionally valued at a premium of $1 to Dubai quotes, the highest since early June, up from 90 cents on Thursday and discounts as deep as 30 cents last month. OMA-1Mmog-A Some traders said larger-than-usual volumes of Iraqi Basrah Light were also heading to the Mediterranean, tightening supplies in the Mideast Gulf and leaving less for shipment to Asia, where crude requirements are also rising seasonally. The Dubai swaps also reflected a strengthening market, with the premium of October swaps above the November contract at 27 cents, up from premiums of around 20 earlier this week. This deeper backwardation, as this market structure is known, denotes tighter supplies. Traders were also awaiting publication of Saudi official selling prices (OSPs) for October, which were expected to climb across the board because of anticipated higher Asian demand. * EAST-WEST - The Brent/Dubai Exchange of Futures for Swaps (EFS) for October fell 8 cents to $5.06 a barrel at 0830 GMT, Reuters data showed. The front-month EFS on June 15 touched $9.20, the highest intraday value since the spread reached a record of almost $12 in October 2004. * DME OMAN - October Oman traded on the DME rose 11 cents to a premium of $1.02 to Dubai swap quotes at 0830 GMT, using the settlement price for DME futures, the ICE one-minute marker for Singapore and the Brent-Dubai EFS as calculated by Reuters. * MARKET NEWS - China has put the brakes on oil and gas investments in Iran, drawing ire from Tehran over a pullback that officials and executives said reflected Beijing's efforts to appease Washington and avoid U.S. sanctions on its big energy firms. - Oil output in Russia, the world's top crude producer, hit a new post-Soviet high of 10.28 million barrels per day (bpd) in August on the back of production ramp-ups at TNK-BP and Gazprom , the Energy Ministry said on Friday. - Oil companies in Europe are betting on the survival of President Bashar al-Assad in Syria, in contrast to their support for Libya's opposition six months ago, even as the European Union is expected to slap oil sanctions on Damascus. * CRACK SPREADS - Fuel oil's October crack was unchanged at a discount of $6.87 a barrel to Dubai crude, while the November crack was 21 cents weaker at $6.90. - Gas oil's October crack slipped 43 cents to a premium of $17.86, while the November premium was down 42 cents to $18.19 a barrel to Dubai crude. - Naphtha's CFR Japan October crack to Brent strengthened $1.24 to a discount of $5.30, while the November discount also narrowed $1.31 to $4.89 a barrel. * OUTRIGHT PRICES - October ICE Brent LCOc1 was at $113.83 a barrel at 0830 GMT, down 17 cents from the same time on Thursday.

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