Equity benchmark indices Sensex and Nifty fell sharply by nearly 1 per cent on Thursday, continuing their weak momentum for the fourth straight session, due to renewed concerns over potential US tariff hikes amid widespread selling pressure in global markets.

Deep losses in metal, oil & gas, and commodity stocks amid unabated foreign fund outflows added to the pressure, analysts said.

The 30-share BSE Sensex tanked 780.18 points, or 0.92 per cent, to settle at 84,180.96. During the day, it plummeted 851.04 points, or 1 per cent, to 84,110.10.

The 50-share NSE Nifty tumbled 263.90 points or 1.01 per cent to 25,876.85.

From the 30-Sensex firms, Larsen & Toubro, Tech Mahindra, Tata Consultancy Services, Reliance Industries, Tata Steel, and Trent were among the biggest laggards.

On the other hand, Eternal, ICICI Bank, Bajaj Finance, and Bharat Electronics were the gainers.

US President Donald Trump has backed a sanctions bill that could impose 500 per cent tariffs on countries buying Russian oil, giving the White House leverage against countries like China and India to stop them from purchasing cheap oil from Moscow.

US Senator Lindsey Graham on Wednesday said the legislation would give the White House "tremendous leverage" against countries like China, India and Brazil to incentivise them to stop buying cheap oil from Russia.

"Domestic markets extended losses as sentiment turned cautious amid renewed concerns over US tariffs and persistent FII outflows, overshadowing optimism around earnings growth," Vinod Nair, Head of Research, Geojit Investments Limited.

In Asian markets, South Korea's Kospi index was higher, while Japan's Nikkei 225 index, Shanghai's SSE Composite index and Hong Kong's Hang Seng index ended lower.

Markets in Europe were trading marginally lower.

US markets ended mostly lower on Wednesday.

Brent crude, the global oil benchmark, rose 0.75 per cent to USD 60.42 per barrel.

On Wednesday, the Sensex declined 102.20 points, or 0.12 per cent, to settle at 84,961.14. The Nifty went down by 37.95 points or 0.14 per cent to 26,140.75.