Oil slipped toward $77 a barrel on Friday, under pressure from higher Saudi production and trade tensions between the United States and China, although oil supply disruptions lent support.  Top exporter Saudi Arabia told OPEC it raised oil output by almost 500,000 barrels per day last month, OPEC sources said, a sign Riyadh wants to make up for shortages elsewhere and dampen prices. Brent crude LCOc1, the global benchmark, was down 19 cents at $77.20 a barrel by 0910 GMT. U.S. crude CLc1 slipped 2 cents to $72.92. “On the bearish side both Saudi Arabia and Russia are living up to their promise to increase output,” said Tamas Varga of oil broker PVM. “Looming U.S. sanctions on Iran, however, are causing serious concerns amongst market players.” […]