Equity benchmark Sensex tumbled 769 points on Friday, tracking a weak trend in global equities amid escalating tensions between Russia and Ukraine.

Extending its decline for the third straight session, the 30-share BSE index slumped 1,214.96 points to 53,887.72 during the session after a weak start. It finally finished at 54,333.81, lower by 768.87 points or 1.40 per cent.

Similarly, the broader NSE Nifty slumped 252.70 points or 1.53 per cent to close at 16,245.35.

"Global bourses are witnessing a sharp sell-off as reports of Russian attack on Europe's biggest nuclear plant in Ukraine kept tension levels elevated. Rising oil prices along with uncertainties on supply chain disruption have instilled fears that inflation could cross RBI's tolerance level, though temporarily," according to Vinod Nair, Head of Research at Geojit Financial Services.

The domestic market, however, trimmed its losses as buying was witnessed in IT and pharma stocks.

Titan, Maruti Suzuki India, Asian Paints, Mahindra & Mahindra and Hindustan Unilever Limited were the biggest drags on the Sensex, tumbling up to 5.05 per cent.

In contrast, ITC, Dr Reddy's Laboratories, Tech Mahindra and UltraTech Cement were among the gainers.

Bourses in Hong Kong, Shanghai and Tokyo settled significantly lower.

Stock exchanges in the US closed in the negative zone in the overnight session.

Meanwhile, international oil benchmark Brent crude rose 0.80 per cent to USD 111.3 per barrel.

Foreign institutional investors continued their selling spree in Indian markets as they offloaded shares worth Rs 6,644.65 crore on a net basis on Thursday, according to exchange data.