The dollar fell against the euro after the Federal Reserve added to its monetary-stimulus program by announcing plans to buys more Treasuries, renewing concern the measures will debase the U.S. currency.

The U.S. currency weakened after the central bank tied its policies to economic benchmarks and said it will buy an additional $45 billion of Treasuries a month, adding to its third round of quantitative easing, and matching economists’ forecasts.

The Fed said interest rates will stay low “at least as long” as the unemployment rate remains above 6.5 percent and if inflation “between one and two years ahead” is projected to be no more than 2.5 percent. The committee “views these thresholds as consistent with its earlier date-based guidance.”

A Fed program known as Operation Twist, which was designed to hold down borrowing costs by lengthening the average maturity of the Fed’s holdings, will expire at year-end. The central bank kept its target rate for overnight loans between banks between zero and 0.25 percent since December 2008 to spur economic growth.

The yen fell to the weakest in eight months versus the dollar as Japan’s Liberal Democratic Party, which has pledged fiscal stimulus to stoke economic growth, leads in polls before Dec. 16 elections.

In Japan, LDP leader and former premier Shinzo Abe has called for a doubling of the central bank’s inflation goal to 2 percent and “unlimited” easing to end more than a decade of falling prices. The Bank of Japan is due to a hold a monetary policy meeting on Dec. 19-20.