By Ben Eisen, MarketWatch , Hiroyuki Kachi

NEW YORK (MarketWatch)--The U.S. dollar extended gains against rival currencies on Thursday, pushing a widely-watched gauge of the greenback's strength near a four-year high.

The gains come in the wake of a statement from the Federal Reserve that suggested growing confidence in the economic recovery, even as central bankers promised to keep benchmark interest rates near zero for a considerable period. The dollar held most of its gains after a round of mixed economic data.

The ICE Dollar index (DXY), a measure of the dollar against a basket of major currencies, edged up to 86.142 on Thursday, from 85.979 late Wednesday. The index closed in on its highest level since 2010. The dollar index hit 86.64 on Oct. 3.

Here is the economic data that investors watched Thursday:

The WSJ Dollar Index , another gauge of the dollar's strength, slipped slightly to 77.92.

The dollar (USDJPY) was at Yen109.22 from Yen108.90 late Wednesday, while the euro (EURUSD) slipped to $1.2611 from $1.2631. The British pound (GBPUSD) slipped to $1.6002 from $1.6021.

The dollar is "trending upward," said Mizuho Securities chief FX strategist Kengo Suzuki. The FOMC statement reminded the market of the divergence of U.S. and Japanese monetary policies over the mid to longer term, he said.

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