New Delhi, Feb 24 (IANS): India's key indices -- S&P BSE Sensex and NSE Nifty50 -- tanked sharply on Thursday morning as investors remained cautious after Russia announced a military operation in Ukraine.

Reportedly, President Vladimir Putin authorised a special military operation in Ukraine's Donbas region.

At 10.16 a.m., Sensex traded at 55,428 points, down 3.2 per cent or 1,803 points, whereas Nifty traded at 16,545 points, down 3.0 per cent or 518 points.

On the stocks front, all Nifty 50 stocks traded in the red with Tata Motors, Indusind Bank, IndusInd Bank, Tech Mahindra, Bharti Airtel, and Mahindra & Mahindra declining the most during the early trade.

These stocks declined 5.5 per cent, 4.4 per cent, 4.2 per cent, 4.1 per cent, and 4.0 per cent, respectively.

"...Investors should wait and watch the unfolding situation before making any major commitments. Buying should be confined to stocks/ segments which are fairly valued or have good earnings visibility," said V.K. Vijayakumar, Chief Investment Strategist at Geojit Financial Services.

"IT, though highly valued, is a sector whose prospects are steadily improving. There are instances of promoters buying stocks of IT companies. This is an indication of better-than-expected results from the sector. Investors can use sharp market corrections to slowly accumulate high quality stocks in IT."