* Pound hits two-and-a-half-year high on Brexit outlook * Swiss National Bank sticks to policy despite U.S. criticism * Bitcoin rises to record high above $22,800 * Graphic: World FX rates in 2020 tmsnrt.rs/2RBWI5E LONDON, Dec 17 (Reuters) - The dollar fell to its lowest in more than two years against the British pound and euro on Thursday after the Federal Reserve stuck to its current policy while hopes for more U.S. stimulus and a post-Brexit trade deal boosted risk appetite. Congressional negotiators were closing in on a $900 billion COVID-19 aid bill in the United States, according to lawmakers and aides. “While we expect stocks to benefit further from positive news on vaccine rollouts and U.S. fiscal support, the same cannot be said for the U.S. dollar”, said Mark Haefele, chief investment officer at UBS GWM. “Safe-haven demand for the dollar is being eroded by a broadening global recovery.” The dollar index continued to retreat as European markets opened, falling to 89.88 against a basket of major currencies after breaking below 90 for the first time since April 2018.The dollar also s lid to 103.20 yen. The Federal Reserve on Wednesday said it would keep funnelling cash into financial markets until the U.S. economic recovery is secure. The promise of long-term help fell short of some investors’ hopes of an immediate move. The dollar index rose after the Fed’s announcement, but the respite was short-lived. Meanwhile, optimism the European Union and the UK will finally reach a post-Brexit trade deal boosted the pound, which rose to $1.3578, its highest level since May 2018. On Thursday, UK Home Secretary Priti Patel said her government and the EU were in a “tunnel” of negotiations but that her country was ready to face the possibility of no deal. The euro traded at $1.2238, its highest since April 2018. The Swiss franc continued to rise and was at six-year highs of $0.8830 after the Swiss National Bank stuck to its readiness to intervene in currency markets despite being labelled a currency manipulator by the United States. The Treasury said that through June 2020 both Switzerland and Vietnam had intervened in currency markets to prevent effective balance of payments adjustments. China’s onshore yuan traded at 6.5287 per dollar and its offshore counterpart hands at 6.5058, both close to mid-2018 highs. The Australian dollar touched 0.7620 U.S. cents, the highest since June 2018. Also, Bitcoin set an a record high on Thursday, after rising over 6.5% to $22,891, just a day after passing the $20,000 milestone for the first time. (Reporting by Julien Ponthus, editing by Larry King)