The S&P 500 index on Thursday violated a trendline dating back to August as U.S. equities continued to struggle amid escalating oil prices and fears of violence spreading further across North Africa and the Middle East.

The benchmark index hit a session low of 1,297.21, crossing a price trendline connecting lows in late August and late November. This technical weakening could trigger further selling.

The Dow Jones industrial average <.DJI> dropped 104.14 points, or 0.86 percent, to 12,001.64. The Standard & Poor's 500 Index <.SPX> lost 10.18 points, or 0.78 percent, to 1,297.22. The Nasdaq Composite Index <.IXIC> fell 7.65 points, or 0.28 percent, to 2,715.34.

(Reporting by Rodrigo Campos; Editing by Jan Paschal)