The Indian stock markets key indices Sensex and Nifty tumbled more than 2 per cent on Monday as crude oil prices surged to a seven-year high in the international markets amid intensifying tensions between Ukraine and Russia.

The benchmark Sensex started the Monday trade deep in the red at 56,720.32 points and slumped to a low of 56,612.07 points in the morning trade, 1540.85 points down from its previous session's close at 58,152.92 points.