Stock market benchmark indices tumbled on Thursday, with the Sensex cracking 706 points, as the additional 25 per cent tariff imposed by US President Donald Trump on India for its purchases of Russian oil came into effect.

Besides this, persistent foreign fund outflows also dented investors' sentiment.

The additional 25 per cent tariff imposed by the US on India came into effect on Wednesday, bringing the total amount of levies imposed on New Delhi to 50 per cent.

The 30-share BSE Sensex tanked 705.97 points or 0.87 per cent to settle at 80,080.57. During the day, it dropped 773.52 points or 0.95 per cent to 80,013.02.

The 50-share NSE Nifty dived 211.15 points or 0.85 per cent to 24,500.90.

From the Sensex firms, HCL Tech, Infosys, Power Grid, Tata Consultancy Services, HDFC Bank, Hindustan Unilever, Bharti Airtel and ICICI Bank were among the major laggards.

However, Titan, Larsen & Toubro, Maruti and Axis Bank were among the gainers.

"Domestic equities ended lower as pessimism took hold following the implementation of tariffs on Indian goods, dampening investor sentiments. While the cotton import duty exemption briefly lifted hopes of policy support to counter tariff impacts, triggering a short-lived intra-day recovery, investor mood remained fragile, with largecaps declining and mid and smallcaps underperforming amid risk-off sentiment," Vinod Nair, Head of Research, Geojit Investments Limited, said.

The government on Thursday extended duty-free import of cotton by three more months till December 31 to support textile exporters facing steep 50 per cent tariffs in the US.

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

European markets were trading on a mixed note.

The US markets ended in positive territory on Wednesday.

Global oil benchmark Brent crude dipped 0.62 per cent to USD 67.63 a barrel.

Foreign Institutional Investors (FIIs) offloaded equities worth Rs 6,516.49 crore on Tuesday, according to exchange data. DIIs, however, bought stocks worth Rs 7,060.37 crore.

The domestic equity markets were closed on Wednesday on account of Ganesh Chaturthi.

On Tuesday, the Sensex tanked 849.37 points or 1.04 per cent to settle at 80,786.54, and the Nifty dropped 255.70 points or 1.02 per cent to 24,712.05.