Brent dips towards $109 on euro zone downgrade risk

SINGAPORE (Reuters) - Brent crude fell towards $109 on Tuesday, as a warning by ratings agency Standard & Poor's that it might downgrade euro zone countries tempered hopes for a concrete resolution to the region's debt crisis. The S&P news also overshadowed ongoing tensions between OPEC producer Iran and the West that could lead to crude supply being disrupted from the world's fifth-largest