* EM stocks rise nearly 4% for the week * MSCI EMFX index to log highest weekly gain since May * S.African rand, Brazil’s real among top weekly gainers * Powell’s speech at Jackson Hole awaited Aug 27 (Reuters) - Emerging market stocks were flat on Friday in cautious trading ahead of a much awaited speech from Federal Reserve boss Jerome Powell at an annual conference, still eyeing their best week since February, while Russia’s rouble rose on higher oil prices. Investors have been following the virtual Jackson Hole symposium which began late on Thursday, but most of the attention will be on Powell’s speech at 1400 GMT (10 a.m. ET), where he is expected to hint at whether the U.S. central bank will indeed scale back on its massive pandemic-era stimulus. Emerging market currencies have had a decent week of gains on the back of a weakening dollar, which suggests most traders have already scaled back their expectations of the Fed making any changes to its ultra-loose monetary policy. “The reason is likely to be the uncertainty surrounding the spread of the Delta variant,” Thu Lan Nguyen, FX and emerging markets analyst said. “Why should Powell of all things today announce something, if the next monetary policy meeting is taking place only in about a month? And before that, important data such as the U.S. labour market report and consumer price data for August are yet to be published.” The MSCI’s index for developing world currencies is up 0.7% for the week, set for its best performance in three months, while its stocks counterpart is up almost 4% for the week as it eyes its biggest weekly gain in nearly seven months. Russia’s rouble strengthened 0.6% against the dollar as it found support in rising oil prices amid worries about supply disruptions as energy companies began shutting in production in the Gulf of Mexico ahead of a potential hurricane forecast to hit on the weekend. The South African rand rose 0.3%, set for weekly gains of over 2%, as data earlier in the week showed a rebasing of gross domestic product that was 11% bigger in 2020 than previously thought. The Brazilian real was also among top weekly performers, set for a 2% rise this week. The Turkish lira was up 0.2% after data showed the country’s economic confidence index rose to 100.8 points in August. A reading above 100 on the index points to an optimistic outlook. For GRAPHIC on emerging market FX performance in 2021, see tmsnrt.rs/2egbfVh For GRAPHIC on MSCI emerging index performance in 2021, see tmsnrt.rs/2OusNdX For TOP NEWS across emerging markets For CENTRAL EUROPE market report, see For TURKISH market report, see For RUSSIAN market report, see Reporting by Shreyashi Sanyal in Bengaluru; Editing by Shounak Dasgupta Our Standards: The Thomson Reuters Trust Principles.