WASHINGTON, April 5 (Reuters) - U.S. Treasury Secretary Janet Yellen said that a $650 billion increase in International Monetary Fund currency reserves will put significant resources into the hands of the world’s poorest countries facing the biggest pandemic needs. Yellen told the Chicago Council on Global Affairs that many advanced economies -- which will get the biggest share of resources from the U.S.-backed Special Drawing Rights allocation -- have indicated a desire and willingness to loan or donate SDRs to poorer countries through IMF facilities. Yellen also said that she doubted that Biden spending initiatives, including a $1.9 trillion relief package and a proposed $2 trillion infrastructure investment plan, would cause inflationary pressures because the true U.S. unemployment rate was still around 9% due to the coronavirus pandemic. (Reporting by David Lawder)