U.S. stocks opened sharply lower on Tuesday as Greece's debt problems continued to rattle investors, with the Nasdaq dropping 2 percent.

Striking public workers in Greece challenged their government's bailout-for-austerity deal with the European Union and the International Monetary Fund as investors worried about Athens' ability to enforce deeper spending cuts.

The Dow Jones industrial average <.DJI> fell 116.31 points, or 1.04 percent, at 11,035.52. The Standard & Poor's 500 Index <.SPX> lost 13.40 points, or 1.11 percent, at 1,188.86. The Nasdaq Composite Index <.IXIC> dropped 43.32 points, or 1.73 percent, at 2,455.42.

(Reporting by Chuck Mikolajczak)