SINGAPORE, June 7 (Reuters) - Middle East crude values were steady on Tuesday as participants assessed the impact of lower official selling prices for Saudi light grades and a potential increase in OPEC output ahead of the group's meeting on Wednesday. Spot Oman crude for loading in August was notionally valued at a premium of about 80 cents to Dubai quotes, traders said, in line with the latest deals heard for July cargoes. But no physical deals were heard yet for August lots. Some traders said Oman may drop with the first deals on August supplies, tracking weaker Murban, which was valued at parity with the ADNOC price. A larger-than-expected drop for Saudi Aramco's Arab Light July OSPs set a bearish tone for the market on Monday. Expectations OPEC would at least raise quotas to bring them more in line with actual production also weighed on notional crude values. Saudi Arabia plans to lift oil output by more than 500,000 barrels to day in June to its highest in three years, a senior Gulf industry official told Reuters. [ID:nOPC000061] Demand from Asian refiners over the summer was likely to be lower than expected, some traders said, meaning refiners that were mostly covered for July and August would curb purchases on the spot market. * OSPs - Yemen has set the official selling price of its Masila crude for loading in August at $1.17 a barrel below dated Brent, down from a discount of 87 cents for July. [ID:nL3E7H700Q] - The price was derived from a sale of 2.9 million barrels to China's Unipec via a tender, a source said. - Yemen set the official selling price for Marib Light crude for August at parity to dated Brent, unchanged from July, the government said in a statement. [ID:nL3E7H700Q]] * DUBAI PARTIALS - A total of 13 Dubai 25,000-barrel partials traded on Tuesday, six of them from Chinese trader Unipec. * EAST-WEST - The front-month Brent/Dubai Exchange of Futures for Swaps (EFS), an indicator for the premium of light sweet grades over heavy sour supplies, slipped 9 cents to $6.45 a barrel. It reached $7.86 in April, the widest in more than five years, Reuters data showed. For a graphic of the EFS and the Dubai forward curve: here * DME OMAN - August Oman traded on the Dubai Mercantile Exchange (DME) gained 3 cents to a premium of 74 cents a barrel 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 - Saudi Arabia is planning to lift oil output sharply in June, whatever policy OPEC adopts this week, in an effort to rein in high fuel prices. [ID:nLDE7560QM] - Kuwaiti Oil Minister Mohammad al-Busairi told Reuters on Tuesday he expected OPEC to agree to raise output when it meets on Wednesday. [ID:nOPC000062] - The oil market faces tight supply in the second half of the year, UAE Oil Minister Mohammed bin Dhaen al-Hamli told reporters on Tuesday. [ID:nOPC000063] - Still, world oil markets are well supplied and prices at $100 to $120 a barrel are fair, Iraq's oil minister said on Tuesday, suggesting Baghdad may not see a case for an increase in OPEC's output. [ID:nLDE7560OI] - Royal Dutch Shell (RDSa.L: Quote) expects oil product output at its joint venture gas-to-liquids project in Qatar to start in weeks, bringing online the world's biggest facility built at a cost of about $18-$19 billion. [ID:nL3E7H70EL] * CRACK SPREADS - Fuel oil's July crack weakened 25 cents to a discount of $7.73, while the August crack was 24 cents lower at a discount of $8.30 a barrel to Dubai crude amid higher crude benchmarks and a muted market in early trade. - Gas oil's July crack eased 7 cents to a premium of $20.59 a barrel, while the August crack was 4 cents lower at a premium of $20.89 a barrel to Dubai crude. - Naphtha CFR Japan's July discount to Brent crude inched up 7 cents to $7.94, while the August crack was 5 cents lower at a discount of $7.48 a barrel. * OUTRIGHT PRICES - July ICE Brent LCOc1 was at $114.74 a barrel at 0830 GMT, down 10 cents from Monday. [O/R] (Reporting by Alejandro Barbajosa, editing by Anthony Barker)

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