WASHINGTON, Nov 9 (Reuters) - U.S. Treasury Secretary Janet Yellen said on Tuesday that the bipartisan infrastructure package approved by Congress and President Joe Biden"s proposed social and climate spending plan would increase U.S. productivity and the size of its labor force. Yellen said in prepared remarks to a University of Nevada-Las Vegas economic conference that together, the two bills would increase long-term U.S. economic output without increasing the national debt. "I do believe that the passage of these pieces of legislation will lead not only to higher rates of productivity but to positive changes across a wide array of metrics. They will increase the size of our labor force and expand the productive capacity of our economy," Yellen said.