* Rupiah set for worst day since Feb. 26 * Won hits lowest since May 20 * Taiwan c.bank rate decision due * Graphic: World FX rates tmsnrt.rs/2RBWI5E * Asian stock markets: tmsnrt.rs/2zpUAr4 By Shashwat Awasthi June 17 (Reuters) - Indonesia"s rupiah was set for its worst day in four months on Thursday, as a double whammy of rising COVID-19 cases and a hawkish turn by the U.S. Federal Reserve eclipsed its central bank"s promise to support the currency further. Other emerging Asian currencies were also weaker, led by a 1% slide in South Korea"s won, as the dollar hit two-month highs after the Fed signalled it would raise interest rates earlier than expected and consider tapering bond buying. Bank Indonesia (BI), which has cut rates by 150 basis points and injected over $57 billion worth of liquidity since 2020, met expectations by leaving rates at 3.50% and pledged to further strengthen measures to stabilise the rupiah. The currency fell 0.7% to its lowest level in nearly a month, having weakened as much as 0.9% following the Fed readout overnight and Indonesia"s highest daily COVID-19 infections tally since late-February. Indonesian three-year benchmark yields pared earlier gains and were up 1.1 basis point at 4.659%, while Jakarta"s equity index edged 0.1% lower. Even as rising infections threaten to stifle Indonesia"s economic recovery, "emergent macro-stability risks" limit BI"s options to ease policy further, Mizuho analysts said. "This will be exacerbated following the hawkish surprise from the U.S. Fed overnight, which we expect will increase depreciation pressures on the IDR." BI"s decision also came on the heels of the World Bank suggesting the country keep its monetary policy accommodative and make the rupiah exchange rate flexible amid external pressure. The Fed"s indications on policy tightening could prompt central banks in emerging markets to soon follow suit, which could cycle cash out of those markets. A Reuters poll showed that investors had trimmed long bets on most of Asia"s emerging currencies, partly as they weigh the prospect of tighter monetary settings. "The stage is set for what I feel is a period of somewhat higher volatility as the narrative changes and traders adjust to a future reduction in liquidity conditions," said Chris Weston, head of research at broker Pepperstone. Philippine shares, which have soared more than 11% in the last three weeks, fell over 1% and suffered their biggest one-day drop in more than a month. Outperforming their regional peers, stocks in Thailand gained 0.3% after the government said it planned to reopen the nation to visitors within 120 days and kick-start the tourism-reliant economy. If the government"s plan to fully reopen the country and procure vaccines is successful, it would give the economy a shot in the arm in the country"s peak tourist season in the fourth quarter, analysts at Phillip Capital said in a note. HIGHLIGHTS: ** In the Philippines, top index losers are Bloombery Resorts down 2.4%, Universal Robina down 2.3%, and Ayala Land down 2.3%. ** Top gainers on Thailand"s SETI include Thai Textile Industry up 22.02%, Jasmine Telecom Systems up 18.8%, and Finansia Syrus Securities up 18%. Asia stock indexes and currencies at 0730 GMT COUNTRY FX RIC FX DAILY % FX YTD % INDEX STOCKS DAILY % STOCKS YTD % Japan +0.03 -6.71 -0.93 5.74 China -0.51 +1.53 0.21 1.51 India -0.64 -0.99 -0.32 12.42 Indonesia -0.73 -2.09 -0.06 1.60 Malaysia -0.46 -2.78 -0.50 -3.49 Philippines -0.25 -0.72 -1.23 -3.53 S.Korea -1.17 -3.91 -0.42 13.62 Singapore -0.16 -1.29 0.13 10.54 Taiwan -0.22 +2.63 0.48 18.04 Thailand -0.64 -4.46 0.22 12.35 (Reporting by Shashwat Awasthi in Bengaluru; Editing by Aditya Soni) Our Standards: The Thomson Reuters Trust Principles.