NEW YORK (Reuters) - Oil prices edged higher on Tuesday, touching its highest since May 2015, supported by OPEC-led production cuts and expectations that U.S. crude inventories have dropped for an eighth week. The Organization of the Petroleum Exporting Countries and allies including Russia are keeping supply limits in place in 2018, a second year of restraint, to reduce a price-denting glut of oil held in inventories. Brent crude was up 18 cents at $67.96 per barrel by 11:08 a.m.