SINGAPORE, May 11 (Reuters) - Sweet crude sentiment weakened in Asia on Friday after Vietnam sold Te Giac Trang crude in the first semi-term tender for the grade at the lower end of a premium range fetched for June cargoes. * TENDERS - Vietnam's PV Oil sold Te Giac Trang (TGT) crude for July-December loading to three buyers - Shell, Vitol and Unipec - at a premium between $6.60 and $6.70 a barrel to dated Brent, trade sources said. The exact purchase volume by each buyer was not known, but they will have to lift a minimum 6,700 barrels per day of TGT as requested in the tender. The premium is much lower than PV Oil's offer of $7.65 a barrel and are also at the lower end of the $6.50-$8.00 range fetched for June cargoes. - PV Oil offered in a tender its first cargo of Bintulu crude from its joint venture field in Malaysia, trade sources said. The tender to sell a 300,000-barrel cargo for July 4-5 loading will close on May 18, with bids valid until May 21. * REFINERY - The Royal Dutch Shell 110,000 barrels-per-day Tabangao refinery in Batangas, Philippines, is undergoing planned maintenance, industry sources said. - South Africa's 180,000 barrels-per-day SAPREF refinery has shut one of its secondary units for planned maintenance which is expected to take about three weeks but which will not affect production, a company spokeswoman said. * MARKET NEWS - China's implied oil demand in April dropped to a six-month low and posted its first yearly decline in at least three years, as a sputtering economy and high crude prices combined to squeeze the appetite of the world's second-largest oil consumer. - Tension between Iran and the West is likely to keep oil prices high despite a dramatic improvement in world supply and a big build in stocks, the International Energy Agency (IEA) said. The agency said global oil supply rose 600,000 barrels per day (bpd) to 91 million bpd in April and was now 3.9 million bpd over year ago levels, with 90 percent of the increase coming from OPEC. CRUDE Price Prev Change JUNE Brent 111.76 112.91 -1.15 JUNE Brent/Dubai EFS DUB-EFS-1M 3.66 3.84 -0.18 PRODUCT CRACKS Price Prev Change JUNE fuel oil crack -5.08 -4.70 -0.38 JUNE gasoil crack 16.27 16.67 -0.40 JUNE naphtha crack -10.09 -11.13 1.04 COMPLEX REFINERY MARGINS Today 5.83 Last 5 days 7.36 Last 365 days 7.62

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