* EU officials have discussed idea of ECB lending to IMF * World stocks slip, Wall St indexes mixed * Treasuries prices fall as Italian yields ease modestly By Walter Brandimarte Nov 18 (Reuters) - The euro gained on Friday on hopes that the European Central Bank could get involved in a plan to help struggling euro zone countries but world stocks fell as many investors continued to fear the spreading of the region's debt crisis into core European economies. U.S. stocks traded slightly higher early in the morning on reports that the ECB is considering lending to the International Monetary Fund to bail out troubled euro zone economies. U.S. Treasury prices fell as expectations of greater ECB involvement in seeking a solution to the crisis reduced their safe-haven appeal. "The ECB would have to be involved in any potential solution (for the crisis) for it to be credible, so I would expect that to give the euro a bit of a lift," said Tom Levinson, a foreign exchange strategist at ING. "Whether it will persist or not is highly debatable. This is a knee-jerk euro reaction and I think it will struggle to hold around this level," he added. The euro zone common currency rose 0.4 percent to $1.3509, pulling away from a five-week low of $1.3420 struck on Thursday. Key Wall Street indexes were mixed. The Dow Jones industrial average was up 61.53 points, or 0.52 percent, at 11,832.26. The Standard & Poor's 500 Index was up 4.15 points, or 0.34 percent, at 1,220.28. The Nasdaq Composite Index was down 1.50 points, or 0.06 percent, at 2,586.49. In Europe the FTSEurofirst 300 fell 0.5 percent. World stocks, measured by the MSCI All-Country World Index , declined 0.4 percent. U.S. crude oil was off less than 0.1 percent at $98.76 per barrel. Benchmark 10-year U.S. Treasury notes fell 16/32, sending their yield up to 2.02 percent, as a decline in Italian government bond yields reduced their safe-haven bid. Yields on Italian 10-year bonds eased to 6.7 percent but stayed near levels investors consider unsustainable.