The S-P BSE Sensex and NSE Nifty 50 indexes extended declines in noon deals mirroring losses in other Asian markets after US President Donald Trump stunned markets with tariffs against imports from Brazil and Argentina, recharging fears about global trade tensions, while weak US factory data added to the investor gloom.

The S-P BSE Sensex which opened marginally lower and dropped as much as 223 points to hit an intraday low of 40,579.45 and the NSE Nifty 50 index fell below its symbolically important level of 12,000 for the first time in last seven sessions.As of 11:49 am, the Sensex was down 177 points at 40,625 and Nifty fell 64 points or 0.5 per cent to 11,984.The Reserve Bank of India's bi-annual Monetary Policy Committee meet for December started today.

Economists polled by news agency Reuters expect the central bank to cut interest rate by 25 basis points, for sixth consecutive time, after the country's economic growth fell to 4.5 per cent in September quarter, its worst pace of growth in more than six years.Nine of 11 sector gauges compiled by National Stock Exchange were trading lower led by the Nifty Metal index's 2.7 per cent fall.

Nifty Bank, Financial Services, Media, PSU Bank, Private Bank and Pharma indexes also fell between 0.5-2.5 per cent decline.On the other hand, Nifty Realty and IT indexes were among the gainers, up around 0.5 per cent each.Mid- and small-cap shares were also witnessing selling pressure as the Nifty Midcap 100 index tumbled 1 per cent and Nifty Smallcap 100 index dropped 0.7 per cent.Bharti Infratel was top Nifty loser, the stock declined 7.5 per cent to Rs 245.50.

Yes Bank, Tata Steel, JSW Steel, Adani Ports, Vedanta, Hindalco, Grasim Industries, Bharti Airtel, Zee Entertainment and Tata Motors also fell between 1.5-4.7 per cent each.On the flipside, Bajaj Auto, TCS, Titan, Hero MotoCorp, Infosys, Tech Mahindra and Kotak Mahindra Bank were among the gainers.The overall market breadth was negative as 1,324 shares were declining while 715 were advancing on the BSE.