Fed Vice Chairman Stanley Fischer said at a Saturday event sponsored by the IMF that the global outlook might hamper the effort to normalize U.S. monetary policy after years of extraordinary stimulus.
In addition, Fed Governor Daniel Tarullo said at a conference that he was worried about global growth, while Chicago Fed President Charles Evans said a strengthening of the dollar and weak growth abroad could mean less justification for the Fed to raise rates.
Analysts said the yen, which tends to gain on jitters over global growth, benefited from the dollar's weakness. They said, however, that they viewed the dollar's drop as a potential buying opportunity.
Market holidays in Tokyo and in the U.S. bond market also sapped liquidity, making the dollar's fall more dramatic.
The euro was last up 0.49 percent against the U.S. dollar at $1.2689, just below a session high of $1.2699. The dollar was last down 0.37 percent against the yen at 107.23 yen after hitting 107.07 yen, its lowest level in nearly a month, earlier in the session.
The U.S. dollar index, which measures the greenback against a basket of six major currencies, was last down 0.48 percent at 85.496. The dollar was last down 0.62 percent against the Swiss franc at 0.9516 franc.
On Wall Street, U.S. stocks were lower, with the benchmark S&P 500 stock index last down 0.34 percent.
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