The dollar tumbled on Monday to its lowest level in three years as investor confidence in the U.S. economy took another hit over President Donald Trump's attacks on the Federal Reserve chairman, potentially putting the central bank's independence under threat.

The benchmark dollar index has fallen roughly 5 percent since early April, when Trump roiled markets with his sweeping tariffs.

The dollar was rising as concerns over the Federal Reserve's independence and a U.S.-China trade war ease following remarks from President Trump, Commerzbank's Michael Pfister said in a note. Trump on