* Stimulus driven optimism dents dollar * Crown rises as Norges Bank plans 2022 rate hike * Bitcoin falls 10% * Sterling at fresh 2-1/2 year high vs dollar * Graphic: World FX rates tmsnrt.rs/2RBWI5E LONDON, Jan 21 (Reuters) - The euro clung to its gains on Thursday after the European Central Bank stuck to its monetary policy while expectations of a massive U.S. stimulus package fuelled market optimism and sapped demand for safe-haven currencies like the dollar. The euro gained 0.4% against the dollar and traded at $1.2153 a few minutes after the ECB left its ultra-easy policy unchanged as expected and kept the door open to more stimulus to tackle the resurgent COVID-19 pandemic. “While the idiosyncratic euro story remains unexciting (the euro zone will not outperform the U.S. economy this year and any ECB policy normalisation is a very distant story), we expect the bearish dollar dynamics to dominate”, ING strategists said prior to the ECB announcement. Many analysts expect the dollar to continue its downtrend trend, which saw it lose nearly 7% in 2020 amid ultra-loose U.S. monetary policy and hopes for a post-pandemic global recovery. The U.S. currency typically loses out against its major peers when investors are inclined to take on more risk. Stock markets reached record highs on Wall Street and in Asia following the inauguration of Joe Biden, amid hopes the 46th president of the United States would secure a $1.9 trillion package to prop up the COVID-19 hit economy. The dollar index slipped 0.24% to 90.194, declining for a third day after touching a nearly one-month high of 90.956 on Monday. Norway’s crown jumped 0.8% against the dollar to 8.4268 after the country’s central bank said it planed to raise rates early next year as the economy recovers from the coronavirus pandemic. This could make it the first among G10 central banks to raise the cost of borrowing. Sterling set a fresh 2-1/2 year high against the dollar and a new 8-month high against the euro on Thursday on hopes that Britain’s brisk pace of COVID-19 vaccinations would lead to a relatively quicker rebound in economic growth. The dollar also lost 0.1% at 103.460 yen on Thursday, after dipping to a two-week low of 103.33. The Bank of Japan kept monetary policy unchanged on Thursday while revising up its economic forecast for next fiscal year. The Aussie dollar rose 0.3% to 77.71 U.S. cents, adding to a 0.7% rally in the previous session. Australia boasted another solid rise in employment in December, data released Thursday showed. The U.S. currency slipped against the Canadian dollar, down 0.06% to C$1.2628 after the Bank of Canada opted not to cut interest rates. Bitcoin BTC=BTSP slumped 10% on Thursday to a 10-day low, retreating further from record highs, with traders citing fears of tighter U.S. regulation.