The U.S. economy has strengthened since a slump early this year, the Federal Reserve said Wednesday, but it wants to see further gains in the job market and higher inflation before raising interest rates from record lows.The Fed gave no timetable for a rate hike but said it expects the economy's gains to accelerate later this year. Many analysts say that if the economy keeps improving, the Fed will likely raise its key short-term rate in September. That rate has been held near zero since 2008.A statement issued after the Fed's latest policy meeting noted that the job market, the housing industry and consumer spending are all improving. The Fed's assessment contrasts with its previous statement in April, when it noted that the economy weakened during winter.Among economists, the Fed is seen as wanting to prepare investors for a coming rate hike if the economy continues to improve while stressing the reassuring message that it will raise rates very gradually.The idea is to avoid spooking investors, who are already on edge over the likelihood of a rate hike and the threat of a default by Greece's government. The Fed wants to convince the markets that the economy will be sturdy enough to withstand slightly higher rates.When the Fed last met in April, the economy had just emerged from a stall-out. Growth in the January-March quarter had been depressed by weather that kept consumers home, a labor dispute that disrupted West Coast ports, a stronger dollar that slowed exports and cheaper oil that triggered cutbacks by drilling companies. After its meeting, the Fed gave no indication it was any closer to raising rates.Recent economic reports have turned more buoyant, with a rebound in home construction and retail sales and near-record auto sales.Perhaps most important, the job market has revived, having added an average of 217,000 jobs a month this year. The unemployment rate, at 5.5 percent, is down from 6.3 percent a year ago and 7.5 percent two years ago. Even pay growth, which has languished during the economic recovery, has begun to pick up.All that points to solid economic growth of around 2.5 percent in the current April-June quarter.Yet there are still lingering problems. Though average hourly earnings rose 2.3 percent in May from a year ago, wage increases remain generally sluggish.Other labor market indicators from the number of people jobless for more than six months to the number of part-time workers who would prefer full-time jobs remain at levels the Fed views as subpar.Beyond employment, the central bank has yet to achieve its other mandate promoting stable prices. Inflation has remained persistently below the Fed's 2 percent annual target. Too-low inflation tends to hold back economic growth.Some economists also note that if a Greek default and an exit from the euro currency alliance were to ignite turmoil in global markets, or if investors dumped bonds and sent long-term rates soaring, the Fed might decide to put off a rate increase until next year.The International Monetary Fund this month downgraded its forecast for the U.S. economy and urged the Fed to consider delaying a rate hike until 2016. IMF Managing Director Christine Lagarde said the risks of raising rates too soon and slowing and perhaps wounding the economy before it's reached full strength outweighed the risks of waiting a bit too long and allowing inflation to creep up.