The euro extended declines versus the U.S. dollar on Monday, breaking through support at its 55-day simple moving average level.

The euro was last down 0.3 percent at $1.2656 EUR=, below its 55-day moving average at $1.2677, according to Reuters data. Traders said the next key technical level to be watched is $1.2605, a 50-percent retracement of the euro's rise from a four-year low of $1.1876 in June to its August peak of $1.3334. (Reporting by Vivianne Rodrigues; Editing by James Dalgleish)