* Gold set for third straight weekly drop, biggest since March * Fed outlook and dollar strength weigh on precious metals * GRAPHIC-2016 asset returns: reut.rs/1WAiOSC (Updates prices, adds comment) By Jan Harvey LONDON, May 20 (Reuters) - Gold edged higher on Friday after two days of losses but remained on track for its biggest weekly slide in nearly two months on growing expectations for an increase in U.S. interest rates as soon as next month. Spot gold was up 0.2 percent at $1,257.11 an ounce at 1345 GMT, while U.S. gold futures for June delivery were up $3.30 at $1,258.10. Spot prices are down 1.5 percent this week and facing a third straight week of losses. New York Fed President William Dudley said on Thursday there was a strong sense among central bank officials that markets were underestimating the probability of policy tightening. That came a day after the minutes of the Fed's April meeting revealed that most policymakers felt a rate increase might be appropriate as early as next month, sending gold to a three-week low of $1,244. It has since bounced back, as ultra-low yields and concerns over economic growth lent support. "In a negative gold environment, gold prices would have been much lower after these Fed comments overnight," ABN Amro analyst Georgette Boele said. "The fact that we are around current levels is a sign that investors are buying on dips and see weakness as an opportunity." Gold is highly sensitive to interest rates, gains in which lift the opportunity cost of holding non-yielding bullion. The metal has rallied 18 percent this year as investors bet the Fed would hold off from further increases. The dollar retreated from its highest in nearly two months against a currency basket, but was heading for a third week of gains, keeping up pressure on gold. "The gold environment now is substantially different from what was apparent several weeks ago, when a weaker dollar and a benign rate environment were providing an element of support," INTL FCStone said in a report. "This is no longer the case." Holdings of the world's largest gold-backed exchange-traded fund, SPDR Gold Shares, rose by 4.5 tonnes on Thursday to their highest since November 2013. Gold demand in Asia was subdued this week by a firmer dollar and weak seasonal demand in major trading centres. Among other precious metals, silver was up 0.6 percent at $16.57, while platinum was up 1.5 percent at $1,024.40 and palladium 2.1 percent higher at $566.10. Palladium was the biggest faller of the week, down 4.7 percent. A deepening deficit in the palladium market this year was predicted by industry experts gathered for Platinum Week in London. (Additional reporting by Koustav Samanta and Vijaykumar Vedala in Bengaluru; Editing by David Goodman and David Evans)